LOS ANGELES (CBSLA) – A suspect has been arrested in connection with a massive wildfire threatening the upscale Topanga and Pacific Palisades communities of Los Angeles.

Flames shoot up from the Palisades Fire in rugged terrain near homes above Topanga Canyon Boulevard on May 15, 2021, in Los Angeles, Calif. (Gina Ferazzi/Los Angeles Times/Getty Images)

At a news conference Monday morning, L.A. Mayor Eric Garcetti confirmed that a suspect was arrested in connection with the Palisades Fire Sunday afternoon. The suspect, who was not immediately identified, was receiving medical treatment for smoke inhalation.

The Palisades Fire, which has burned approximately 1,325 acres and is 23% contained as of early Monday evening, forced about 1,000 people in the Topanga area to flee their homes for hours. They were allowed to return at 6 p.m. with proper identification.

“This whole house is all I have,” Ricki Kupferer, a resident, said. “I was concerned about it, but I was concerned about my neighbors — we have a wonderful neighborhood here — my friends, my possessions, obviously. I’m at an age where I don’t think I’d want to rebuild.”

No structures have been damaged and no major injuries have been reported, though one firefighter suffered minor injuries. The fire is burning in rugged terrain with thick brush, and no homes or structures were under imminent danger Monday. The wildfire is burning in an area that is very dry and has not burned in more than 75 years.

More than 540 firefighting personnel with the L.A. city and county fire departments and Cal Fire were batting the blaze, Garcetti said.

An inversion layer was creating cooler temperatures which was helping in the firefight. However, when that inversion layer lifts, the fire could grow or shift, officials warned.

“The weather is our friend, but it also is our challenge,” Garcetti said. “It’s our friend because it caps the fire and the heat, as soon as it lifts, it is something that is a big danger. Usually traditionally around 2 p.m. or so a fire will see that lift, that’s really when a fire takes off…that’s what happened yesterday.”

The cloud cover was also too low to get the tankers in the air. Firefighters were relying on water-dropping helicopters, but were hoping to get tankers in the air once that cloud cover lifts, possibly by Monday afternoon.

“The problem and the challenge of it is when that inversion layer is here it’s very difficult for us to do the sort of air drops that we’d like to get in there and be more aggressive on this fire,” Garcetti added.

Police helicopters allegedly caught sight of a person setting fires Friday night. Investigators with LAFD and LAPD initially detained a person on Saturday, who was questioned and released. The suspect was then arrested Sunday afternoon. Authorities did not immediately confirm if the suspect was a transient.

“We did detain one person and release them, and determine that the first person was not a suspect,” LAFD Fire Chief Ralph Terrazas disclosed in Monday’s briefing. “The second person was arrested yesterday at 2:30 p.m. and is in custody.”

During the news briefing, there was a large group of people protesting against plans from L.A. City Councilman Mike Bonin to put up temporary shelters to house homeless people on the Westside.

The Palisades Fire was first reported at 10 p.m. Friday in the 1800 block of North Michael Lane, in a canyon with steep and difficult-to-reach terrain. It quickly exploded Saturday, spreading northeast.

“It went from 100 acres to 750 acres or so in about an hour,” LAFD Battalion Chief Al Ward explained Sunday.

Firefighters so far have been able to hold the western edge of the blaze and keep the flames from crossing Topanga Canyon Boulevard.

Evacuations were ordered Saturday for two areas in L.A. County, but not within the city of L.A.. Those evacuation orders remained in place Monday morning.

The latest evacuation map for the Palisades Fire burning in Topanga, Calif., on May 17, 2021. (Los Angeles County/ESRI)

The mandatory evacuations were issued for Zone 4: all residents east of Topanga Canyon Boulevard between the Community House and View Ridge Road. Along with Zone 6: Everyone north of Entrada, south of Oakwood Drive and east of the Henry Ridge Motorway.

The city of L.A. issued an evacuation warning Sunday afternoon in Pacific Palisades for all homes north of Chastain Parkway in the 1500 block to Calle Del Cielo. The warning area includes Calle De Sarah, Calle Bellevista and all homes west of Calle Del Cielo and Ave Ashley up to the hills.

Topanga Canyon Boulevard between the Pacific Coast Highway and Mulholland Drive remains closed.

Topanga Elementary Charter School, at 22075 Topanga School Road, will be temporarily closed beginning Monday due to air quality and safety concerns caused by the Palisades fire, the Los Angeles Unified School District reported.

Large animals can be taken to Pierce College Equestrian Center, at 6201 Winnetka Ave. in Woodland Hills. Small animals can be taken to the Agoura Animal Care Center, 29525 Agoura Hills Road in Agoura.

(© Copyright 2021 CBS Broadcasting Inc. All Rights Reserved. City News Service contributed to this report.)