LOS ANGELES (CBSLA.com) —A major emergency fire heavily damaged two vacant apartment buildings in the Westlake District early Thursday morning, but no one was hurt.

The fire broke out at 2:11 a.m. at a Victorian duplex at 681 S. Bonnie Brae St., then jumped to a neighboring four-story apartment building. It was declared knocked down by 161 firefighters within an hour and 26 minutes, according to Los Angeles Fire Department’s Amy Bastman.

READ MORE: Strike Averted: IATSE And AMPTP Have 'Basic Contract' Agreement, Per Officials With The Theatrical Stage Employees Union

At one point, as fire burned inside the building, firefighters went into a defensive mode, fighting the blaze from the exterior.

The large blaze prompted evacuations of the two buildings and residents in a nearby convalescent home were told to shelter in place, Los Angeles Fire spokesman Erik Scott said. A third adjacent building, a law library, was also damaged, but firefighters were able to halt the flames and protect the books inside.

Although the buildings were officially listed as vacant, authorities learned that homeless people may have been squatting in one or both.

“Initial reports from a few of the witnesses were that there may have been some transients in the initial fire building,” LAFD Battalion Chief Ralph Terrazas said.

READ MORE: Taylor's Blunder, Other Missed Chances Put LA In NLCS Hole

Searchers began working after daybreak, assisted by specially trained dogs, to determine if anyone had died in the fire, Los Angeles Fire Department spokesman Brian Humphrey said.

Arson investigators were on scene. Authorities are working to reopen a stretch of Wilshire Boulevard that was closed down for the firefight and investigation, but it may not be reopened till at least noon.

As of late morning, the Victorian house had been red-tagged, and officials were deciding whether to red-tag the apartment building, Humphrey said. Authorities were also considering whether to yellow-tag the convalescent home and the law library, both of which sustained damage.

The cause of the fire was under investigation. A damage estimate was not immediately available.

MORE NEWS: Karen Bass Officially Kicks Off Her Run For Mayor Of Los Angeles At Saturday Event

(© Copyright 2017 CBS Broadcasting Inc. All Rights Reserved. City News Service contributed to this report.)