The number deployed – now 939 – are part of a long-running volunteer programme led by the California Department of Corrections and Rehabilitation (CDCR).

Their numbers have steadily increased since Tuesday, the day the deadly fires began spreading uncontrollably through Los Angeles.

Over 10,000 structures have been destroyed and 37,000 acres burned, as thousands of emergency workers descend on the Los Angeles area to fight the flames.

At least 11 people have been killed in the wildfires, officials said.

The incarcerated firefighters have been drawn from among the 35 conservation fire camps run by the state, minimum-security facilities where inmates serve their time and receive training. Two of the camps are for incarcerated women.

The 900-plus incarcerated firefighters in use account for roughly half of the 1,870 prisoner-firefighters in the scheme.

In the field, they can be seen in prison-orange jumpsuits embedded alongside members of the California Department of Forestry and Fire Protection (Cal Fire).

The incarcerated firefighters have been working “around the clock cutting fire lines and removing fuel from behind structures to slow fire spread”, CDCR told the BBC in an emailed statement.

The programme, which dates back to 1946, has divided critics, who see it as exploitative, and supporters, who say it is rehabilitative.

The state pays inmates a daily wage between $5.80 and $10.24 (£4.75 and £8.38), and an additional $1 per day when assigned to active emergencies.

Those wages are a fraction of the salaries received by citizen firefighters in California, who can earn upwards of $100,000 annually.

“You’re getting pennies compared to the other folks that’s alongside of you. You’re just cheap labour,” Royal Ramey, a former incarcerated firefighter and co-founder of the non-profit Forestry and Fire Recruitment Program (FFRP), told the BBC.

“And if you do pass away while fighting fires, you don’t get any benefits from that,” he continued.

“You’re not gonna get no award. You’re not gonna be recognised as a wildland firefighter,” he said, adding that he would remember in the field that he had already signed his own death certificate.

Still, Mr Ramey said the low pay is more than a California prisoner would otherwise earn performing jobs in the state penitentiaries.

The conservation camps and their “park, picnic-type feel” also offer additional perks like better food, he said, compared to California’s notoriously dangerous and overcrowded prisons.

“It’s a better living situation, definitely,” he said.

Camp participants can also earn time credits that help reduce their prison sentences, CDRC said.

Inmates convicted of crimes categorised as “serious” or “violent” felonies are not eligible to participate.

After incarcerated firefighters are released from prison – having been trained by the state – many try to get hired as citizen firefighters, but are denied, Mr Ramey said.

“There’s a stigma to it. When people think of firefighters they think of some clean-cut guy, a hero, not someone who’s been locked up,” he said.

He launched his nonprofit to help formerly incarcerated firefighters overcome the barriers and help fill the firefighter shortage California has faced for years.

There are currently five wildfires burning through billions of dollars worth of structures in the Los Angeles area, predicted to be one of the most expensive in history.

Strained for resources, the state has called on over 7,500 emergency personnel and first responders, including the state and National Guard and firefighters from as far away as Canada.

The fires have still been difficult to contain and continue to spread, with 35,000 acres from the two largest fires, Palisades and Eaton, already burned.