Last updated 2:11 p.m.

BIDDEFORD, Maine — Investigators say a suicidal woman was shot to death by a Biddeford police officer while holding what turned out to be a BB-pellet handgun.

Barbara Stewart, 47, was shot three times on a sidewalk Tuesday night after she refused orders to drop the weapon and approached officers in a threatening manner, according to state and local investigators. It was the first fatal police shooting in Biddeford in at least four decades.

It all started at 7:18 p.m. with a 911 call by a woman threatening to kill herself.

Minutes later, officers found the woman on a sidewalk along Main Street. Lt. Jeffrey Green, one of three officers, fired when she approached officers, police Chief Roger Beaupre said.

“We were responding to help this person, to give them the care they need. It is a situation no one ever wants to see,” he told the Journal Tribune newspaper.

The officer who fired his gun was an eight-year veteran of the police force, Beaupre said.

The entire incident was caught on a camera mounted inside a police cruiser, and several neighbors also saw or heard the incident, he said.

Just last week, Biddeford police received training on use of deadly force from Brian MacMaster, chief of investigations for the attorney general’s office.

The attorney general’s office is leading an investigation into whether Green’s actions were legally justified, meaning he discharged his gun either in self defense or to protect the lives of others, said Kate Simmons, spokeswoman for the attorney general office.

Sue Skillings and Patrick Flannery, who lived nearby, heard the commotion. Skillings said she heard three shots. Afterward, Flannery said an officer rolled the victim over and checked for a pulse. The woman was later pronounced dead at Southern Maine Medical Center in Biddeford.