When a gunman opened fire with an AR-15 at a large high school in south Florida, the 17 dead included students and school workers, young and old.

Here is a look at some of some of those who lost their lives in the massacre at Marjory Stoneman Douglas High School. 

Alyssa Alhadeff, 14 –

An amateur soccer club said one of its players, Alyssa Alhadeff, was among the students killed in the mass shooting at Marjory Stoneman Douglas High School.

Parkland Soccer Club posted on its Facebook page that Alhadeff was a "loved and well respected member of our club and community."

The club posted a note it said was from her family which read: "To Alyssa's Friends honor Alyssa by doing something fabulous in your life. Don't ever give up and inspire for greatness. Live for Alyssa! Be her voice and breathe for her. Alyssa loved you all forever!"

Scott Beigel, 35 –

Students said geography teacher Scott Beigel, 35, helped them enter a locked classroom to avoid the gunman and paid for the brave act with his life.

"If the shooter would have come into the room, I probably wouldn't be speaking to you now," student Kelsey Friend told Good Morning America.

Friend said when she heard gunshots and realized it wasn't a drill she followed other students toward the classroom.

Beigel "unlocked the door and let us in," she said. "I thought he was behind me, but he wasn't. When he opened the door he had to relock it so we could stay safe, but he didn't get a chance to."

Student Bruna Oliveda said she saw Beigel blocking the door.

"I don't know how we're alive," she said.

Martin Duque Anguiano, 14 –

Shooting victim Martin Duque was one of Isaac Briones' best friends.

"He was like, one of the nicest people I knew," said Briones, 15. "He was so caring."

Briones said he last saw Martin the day of the shooting during first period.

"We were just playing around, talking about jokes and stuff," said Isaac, who was outside the school Thursday with others holding a group of white balloons for the victims.

On Instagram, Miguel Duque wrote that words can't describe the pain of losing his brother. He added: "I love brother Martin you'll be missed buddy. I know you're in a better place. Duques forever man I love you junior!!! R.I.P Martin Duque!"

Nicholas Dworet, 17 –

(Facebook via AP)

Nicholas Dworet had committed to swim for the University of Indianapolis.

The college announced Thursday that the senior was among those killed in the mass shooting at his high school.

In a statement, UIndy swimming coach Jason Hite called Dworet an "energetic and very vibrant kind" who cheered for his soon-to-be university during a swimming meet last month.

"I spoke with his mom this morning, and she reiterated the fact that he was really looking forward to this next step in his life and becoming a Hound," said Hite. "He really felt like he had a family in the team, and was really excited about what we're doing up here."

Aaron Feis, 37 –

(Facebook via AP)

Assistant football coach Aaron Feis was shot to death while selflessly shielding students from bullets. A tweet from the school football program ended: "He died a hero and he will forever be in our hearts and memories."

Feis graduated from the school in 1999 and worked mainly with the junior varsity, the team website said. It said he lived in nearby Coral Springs with his wife and daughter.

The team website said Feis spent his entire coaching career at Marjory Stoneman after playing there as a student.

The Sun Sentinel reported that Feis, acting as a school security guard, responded to the original call on a school walkie-talkie. Someone on the radio asked if loud sounds they heard were firecrackers, said football coach Willis May, who also carries a radio.

"I heard Aaron say, 'No, that is not firecrackers.' That's the last I heard of him," May said.

Jaime Guttenberg, 14 –

(Abbie Youkilis via AP)

Ninth grader Jaime Guttenberg, 14, loved to dance and hoped to become an occupational therapist and mother, aunt Abbie Youkilis said.

"She always looked out for the underdog and the bullied and she probably had been kind to the (former) student who shot her," Youkilis said in a written statement sent to The Associated Press.

Guttenberg leaves her parents, Fred and Jennifer Guttenberg, and brother Jesse. Her father said in a Facebook post that he is "trying to figure out how my family gets through this."

Youkilis called for gun-control legislation, saying Jaime's parents were "the world's most loving and over-protective parents but they could not protect Jaime from the sickness that has gripped our country."

Christopher Hixon, 49 –

(Susan Stocker/South Florida Sun-Sentinel via AP)

A married father of two and the athletic director at Marjory Stoneman Douglas High School, Chris Hixon wasn't shy about jumping in wherever he was needed, said friend and one-time colleague Dianne Sanzari.

Hixon belonged to a Roman Catholic church in Hollywood. The Archdiocese of Miami confirmed his death Thursday.

When a volleyball team needed a fill-in coach, Hixon took over; the same thing happened with the wrestling team, Sanzari said. And when the school needed someone to patrol the campus and monitor threats as a security specialist, Hixon did that, too.

It was in that security role that Hixon apparently came within range of the shooter.

Luke Hoyer, 15 –

Fifteen-year-old Luke Hoyer was a loving, sweet person who loved basketball and "smiled all the time," his aunt Joan Cox said.

"He was just a good kid ... very loving and just enjoyed life," said Cox, of Greenville, South Carolina.

She said Luke's parents, Gena and Tom Hoyer, searched for their son at hospitals before finally going to the law enforcement command center, where they eventually learned he had died.

"It's just a terrible thing," said Cox, who said the family — including Luke's older sister Abby and brother Jake — spent Christmas with her and other family in South Carolina. "We just all pretty much can't get over it."

Cara Loughran, 14 –

Cara Loughran, 14, was an excellent student who loved the beach and her cousins, according to her family.

An aunt, Lindsay Fontana, wrote on Facebook: "I had to tell my 8-year-old daughters that their sweet cousin Cara was killed in the shooting at Stoneman Douglas High School yesterday. We are absolutely gutted."

"While your thoughts are appreciated, I beg you to DO SOMETHING," she wrote. "This should not have happened to our niece Cara and it cannot happen to other people's families."

Loughran's neighbor posted a picture of her cheering on a young boy riding a bike with training wheels.

"RIP Cara," Danny Vogel wrote, "and fly with the angels. You will be greatly missed, and we will always love you and celebrate your beautiful life."

Gina Montalto, 14 –

(Facebook via AP)

Shooting victim Gina Montalto was a 14-year-old freshman who participated on the winter color guard squad at the school.

Friends and relatives posted tributes on Facebook, including mother Jennifer Montalto.

"She was a smart, loving, caring, and strong girl who brightened any room she entered. She will be missed by our family for all eternity," said the post.

One of Montalto's color guard instructors from middle school, Manuel Miranda, told the Miami Herald that Montalto was "the sweetest soul ever."

"She was kind, caring always smiling and wanting to help," Miranda said.

Joaquin Oliver, 17 –

(Courtesy of Tyra Hemans via AP)

Joaquin Oliver was known by his nickname "Guac," short for "guacamole," because many couldn't pronounce his first name.

"My friend will literally never get to say, 'I graduated high school,'" said Tyra Hemans, a 19-year-old who said she had been friends with Oliver since they were freshmen.

Hemans said she last saw her friend at school the day of the shooting.

"It was just a brief 'Happy Valentine's,'" she said. "He was with his girlfriend and I was just like, 'Oh my God, you guys are so cute.'"

She added, "He's just a goofball. He's the only kid you'd know that would dye his hair bleach-blond, walk around school, put some tiger stripes in and just be unique. He was a unique soul."

Alaina Petty, 14 –

Fourteen-year-old Alaina Petty was among those who died in the shooting, great-aunt Claudette McMahon Joshi confirmed in a Facebook post.

"There are no hashtags for moments like this, only sadness," she wrote, asking people to lift up Petty's family in prayer.

Petty attended a local Church of Jesus Christ of Latter-day Saints. Petty was a "valiant young member of the Coral Springs Ward," Church leader Stephen E. Thompson wrote in an update.

Meadow Pollack, 18 –

Meadow Pollack's parents called her phone repeatedly only to hear it ring, as they kept an anxious vigil outside the hospital. But on Thursday, her father, Andrew Pollack, confirmed that his daughter was among the dead, the Palm Beach Post reported.

Eighteen-year-old Pollack, a senior, had planned to attend Lynn University, her father said.

"Her life was taken way too soon and I have no words to describe how this feels," friend Gii Lovito posted on Facebook.

Family friend Adam Schachtel said in a Facebook post that "an angel was taken away from us in that horrific tragedy ... no words can be said so just prayers and sadness."

Helena Ramsay, 17 –

Helena Ramsay was soft-spoken, but also smart and a go-getter, her cousin Sefena Cooper said Thursday.

The 17-year-old junior especially loved hanging out with friends and family, "and for this to happen is heartbreaking," Cooper said.

"Although somewhat reserved, she had a relentless motivation towards her academic studies and her soft warm demeanor brought the best out in all who knew her," another relative, Curtis Page Jr., wrote on Facebook.

"She was so brilliant and witty, and I'm still wrestling with the idea that she is actually gone," he wrote. "She would have started college next year."

Another cousin, Jamie Page, called Ramsay "a genuine, beautiful, and smart human being who had so much potential and the brightest future."

Alexander Schachter, 14 –

Trombone and baritone player Alex Schachter was a "sweetheart of a kid," according to a social media post by his family.

In honor of his 14-year-old freshman son, a relative wrote on a gofundme page that the family was starting a scholarship fund "to help other students experience the joys of music as well as fund increased security at schools."

Band director Alexander Kaminsky told the Sun Sentinel that Schachter began playing brass instruments in middle school. He was "fairly quiet" but worked hard to establish himself, Kaminsky said.

"The improvement I witnessed from him was admirable and inspiring," Kaminsky said. "I felt he really had a bright future on the trombone."

His mother died at an early age, and father Max Schachter often visited the school to help out. An older brother, who also attends Stoneman Douglas, survived the attack.

Carmen Schentrup, 16 –

Carmen Schentrup was a smart girl with a sweet smile.

In September, she was named one of 53 National Merit Scholarship Program semifinalists in the county and a classmate tweeted "we all praised for her intelligence."

Cousin Matt Brandow posted on Facebook that the 16-year-old visited Washington State recently and said she wanted to go to the University of Washington. He asked: you like the rain?

"She answers, I hate sweating in the humid Florida weather," Brandow wrote. "That's when I knew you were perfect for Washington."

Peter Wang, 15 –

Peter Wang, a 15-year-old ROTC student at Marjory Stoneman Douglas High School, wasn't interested in status but wanted to help others, relatives said.

A cousin, Aaron Chen, told the Miami Herald that Wang was last seen holding a door open so others could get away from the gunman.

Friends and relatives first thought Wang was just missing and checked with area hospitals. They later found out he had been killed.

"He wasn't supposed to die," Chen told First Coast News.