AUGUSTA — A man is in custody following the discharge of a firearm inside a Walmart store in Augusta.

Police told WCSH that a suspect entered the store around 8 p.m. with a firearm, and a confrontation ensued with another person inside —  referred to by police as a “good Samaritan” — who was trying to disarm the man with the firearm. They said one shot was fired within the building.

While police were responding to the incident inside the store, a woman passed away in the parking lot, according to Augusta Police Deputy Chief Jared Mills.

The woman’s cause of death was not immediately known, but Mills said it wasn’t due to “a gunshot wound or anything that was apparent” and that police would be working with the Medical Examiner’s Office to determine exactly what happened.

On Monday night, police had blocked the west entrance to the store with crime scene tape and Walmart employees in the parking lot were letting people know the store was closed.

One witness, visibly shaken and trying not to cry, stood in the nearly vacant parking lot waiting to give a statement to police, said she was not far from where the shot was fired and ran out of the store. She declined to give her name.

April Murray, of Augusta, arrived at Walmart after the shot was fired and was unable to go into the store. She said she saw a woman in the parking lot who appeared to be having trouble breathing.

Kari Glover, of Waldoboro, said she arrived just after the shot was fired and witnessed the woman in distress. Glover said she heard the woman, who appeared to be in her 60s or 70s, screaming in her car. After that, the man with her said she had stopped breathing.

While help was being administered to the woman, Glover said she saw the police leave the store with the suspect in handcuffs. Police did not immediately release the identity of the suspect.

Kennebec Journal Staff Writer Jessica Lowell contributed to this story.