A bystander who police said helped a woman who was being assaulted by her boyfriend shot and killed the man in a bank parking lot Wednesday night.

Officers were called to a shooting in the Wells Fargo Bank parking lot, in the 1700 block of West Valencia Road, just after 7:30 p.m. and located a man with gunshot wounds. Despite first aid, the man was pronounced dead at the scene. Police identified him as Juan Carlos Velderrain, 32.

Detectives determined that Velderrain was physically assaulting his girlfriend in the bank's parking lot before the shooting. The woman managed to get away from Velderrain and approached a bystander for help. The woman got into the bystander's vehicle as Velderrain verbally confronted them, police said.

During the confrontation, the bystander, an adult male, pulled a handgun and shot Velderrain, police said.

The woman sustained injuries from the assault, police said.

The bystander was interviewed by police at the scene and no arrests have been made. Detectives will complete the investigation and forward the case to the Pima County Attorney's Office for a review of possible charges.

Anyone with information on the incident can all 88-CRIME.