LOS ANGELES (CBSLA.com) — A 25-year-old woman was trapped in an apartment building fire early Monday morning in the Westlake District, officials said.

The fire broke out on the third floor of a four-story building just before 3:40 a.m. at 511 South Park View Street, the Los Angeles Fire Department said.

The fire forced the evacuation of 150 residents as it spread to the fourth floor.

Firefighters located the woman who was trapped and brought her to safety, according to officials.

Two people were treated for smoke inhalation at the scene and released, officials said.

It took 81 firefighters 39 minutes to extinguish the blaze, officials said.

Arson investigators are trying to determine how it started, but officials say the fire was likely accidental.