BUFFALO, N.Y. — Support is pouring into the city of Buffalo following the deadly mass shooting over the weekend.

“Let’s wrap our arms around the families of those precious lives that were lost," said Buffalo Mayor Byron Brown. "We are a strong community, we have to grieve, we have to come together and we have to move forward as a community.”

That was the message from Mayor Brown on Monday as the investigation continues into the shooting at the Tops grocery store on Jefferson Avenue. Police say a gunman opened fire at the store on Saturday, killing 10 people and wounding three others.

For the past day or so, the investigation into the incident was focused on the parking lot where police say the attack began.

On Monday investigators are now going inside the grocery store for the first time since the shooting. FBI agents were seen getting dressed in protective clothing and coverings for their shoes in preparation for going inside to start collecting evidence.

This is expected to be a lengthy investigation as it is being considered a hate crime. Authorities say the suspect specifically targeted a Black community.

On Saturday, police say 18-year-old Payton Gendron live-streamed as he opened fire on men, women and children who were running weekend errands at the store. He was dressed in military gear, police say, armed with a modified AR-15. 

Gendron allegedly first opened fire in the parking lot, shooting four people, three of them fatally, according to investigators. 

Then, as the suspect entered the Tops store, he was confronted by a retired BPD officer who was working as a security guard. Aaron Salter, 55, shot the suspect, but because of the body armor that police say Gendron was wearing, the shot had no effect.

Salter was then shot and killed by Gendron, police say.

Salter is being hailed as a hero with state leaders saying because of his bravery, there is no doubt that people were able to escape with their lives.

According to authorities, a total of 13 people were shot. Of those, 11 were Black. Ten of the victims died, police say.

Multiple law enforcement sources say that investigators do believe a 180-page manifesto, uploaded to the internet, came from the alleged shooter, Gendron, who is from Conklin, New York.

Spectrum News 1 has obtained a copy, which is filled with racist and antisemitic, anti-immigrant language and imagery, as well as a hand-drawn map of the store and detailed descriptions of the weapons he would use.

Investigators say Gendron targeted the neighborhood because of its location in a heavily Black and minority populated area of Buffalo.

Mayor Byron Brown says members of law enforcement at every level are involved in the investigation. He says they're trying to figure out how to prevent this from ever happening again.

The mayor says he has even spoken over the phone with the national head of the FBI.

"[He] expressed his concern and support for this community and indicated that every resource of the federal government will be applied to addressing this issue,” said Brown.

The suspect remains at the Erie County Jail on suicide watch and isolated from other inmates. Police say he pleaded not guilty to a murder charge. 

Authorities executed warrants at his Conklin home, 200 miles away from Buffalo, and his parents are cooperating.

As the investigation continues, Buffalo is still coming to terms with what happened. 

A half-dozen memorials have been put up since the tragedy and they have only grown since. 

Donations from the community are also pouring in as the Tops is one of the only locations on the east side of Buffalo to buy food. The area is known as a food desert.