AUBURN, Maine — An elderly woman was killed Tuesday in an overnight fire at 6 Second St.

A passerby called for help at 2:58 a.m. after spotting the flames. Firefighters knocked down her door and found the woman unconscious inside, according to Deputy Chief Geoff Low.

She died at the scene.

Her identity is being withheld as police try to reach her family.

“It’s under investigation and it’s not suspicious,” said Lowe. “It looks like an unfortunate circumstance.”

A dog, cat and bird also died in the fire.

The building at 6 Second St. had two apartment units, but the woman was the building’s only occupant.

It took firefighters about 30 minutes to get the fire under control, according to Battalion Chief Richard McFadden. The fire is believed to have started in the cellar, he said.

The State Fire Marshal’s Office is investigating, along with city police, fire and the electrical division.

According to property records in Auburn, the building is owned by Peter and Hermina Hart of Lisbon Falls.