Survivors patrol as looters prey on fire-wrecked Los Angeles

People forced to flee their homes by massive wildfires tearing through Los Angeles were taking turns to patrol their streets to ward off looters on Thursday.

At least 20 people have been arrested in the aftermath of massive fires that have razed whole neighborhoods, officials said.

Police warned that officers were flooding the affected areas and would challenge anyone they thought should not be there.

With such a huge area scorched by the fires, which are ravaging the well-to-do Pacific Palisades and another area around Altadena, evacuees feared not enough was being done.

Some are taking matters into their own hands.

One man whose house was one of just a handful left standing on a burned-out Altadena street told AFP said he was working with his neighbors.

ALSO READ: Trump intel advisor Devin Nunes still dismisses Russian election meddling as a 'hoax'

"We're so stressed about this looting happening all around that my neighbors were on watch all last night for several houses in the neighborhood," said the man, who did not want to give his name.

"I'm supposed to take over for them tonight."

Los Angeles County Sheriff Robert Luna said his officers were pushing into fire-wrecked areas and evacuation zones to try to deter wrongdoers.

"We continue to conduct roving patrols, manning hard road closures, providing security in evacuation areas to prevent anyone who may be tempted to engage in criminal... behavior like looting," he told a press conference on Thursday.

He said the bar for arresting people in an evacuation zone was low, and warned that his officers would pounce.

"When we have an evacuation order by law, if you remain in that area, you are guilty of a misdemeanor. If you commit certain crimes, it could jump up to a felony," he said.

"If you are in one of these areas and you do not belong there, you are going to be subject to arrest."

Los Angeles County District Attorney Nathan Hochman said anyone the sheriff's department handed over to his office would be dealt with severely.

"If you want to go ahead and loot, if you want to commit burglary, if you want to engage in grand theft... you will be arrested, you will be prosecuted, and you will be punished to the full extent of the law," he said.

Hochman said no one should think that taking property from an evacuation zone was a small matter.

"It's a huge deal. These acts are despicable, and we will prosecute them with maximal punishment."