CHEEKTOWAGA, N.Y. -- Police credit years of training and the bravery of civilians for preventing Tuesday afternoon's shoot-up of a Dollar General on Union Road in Cheektowaga from turning into a very different scenario. 

Police Chief David Zack said a number of private citizens realized what was going on when Travis Green, 29, started shooting inside the store.

"These people were proactive. They saw a threat. I don't recommend engaging someone with an AR-15. They were not going to be victims. They took this guy out. They put a stop to it," Zack said.

Surveillance video from a police cruiser dashboard camera showed officers running a man down and knocking him over a guard rail a few hundred yards from the store.

Police found 20 spent bullet casings and another 850 live rounds in a vehicle in the Dollar General parking lot. "It's safe to assume his intent was to do significant harm," Zack said. 

He added that the 53-year-old victim, who had been shot in the shoulder, had been treated for injuries and released from ECMC. The victim's name has not been released. 

Green acted alone and there is no indication anyone else was involved in the shooting, Zack said. Green is not cooperating with police as they continue their investigation, he added.

Green appeared Wednesday in Cheektowaga Town Court, where he was charged with second-degree attempted murder, criminal use of a fire arm, reckless endangerment and second-degree assault. He might also face charges related to violations of New York's gun control law, the SAFE Act.

Viola Green, Travis's mother, said the shooting happened shortly after Green had a fight with his estranged wife.

“He was upset, because his wife wouldn’t open the door where she works at to get the vehicle, so he could have left and left with me so she triggered it," Viola said. "I feel she knew he was going to get his weapons. All she had to do was open the door and let him in."

The FBI is also involved in the investigation but it does not appear that the shooting was terrorism-related, Zack said.

Police also confirmed that they are looking at newly-surfaced video, showing a man with face paint and gradually adding weapons while audio from horror film series "The Purge" plays in the background, but initially believe it is Green. It is unclear when that video was posted online.