A fire and an explosion near downtown Los Angeles on Saturday left 11 firefighters injured, according to the fire department.

Firefighters arrived on scene around 6:30 p.m. PT, according to Fire Chief Ralph Terrazas.

While firefighters initially reported "moderate smoke" at the scene, Terrazas said they began an evacuation because of rising heat and smoke. The explosion occurred as the firefighters left the building.

According to Terrazas, a witness told officials firefighters were seen escaping from the roof with their coats in flames.

Dr. Marc Eckstein, LAFD's medical director, said 11 firefighters were taken to County-USC Medical Center. All of them were "awake and alert" on arrival, and all are expected to survive. The injuries ranged from first- to third-degree burns. At least one firefighter is expected to require skin grafts.

Four were taken to the burn intensive care unit, while the others were taken to the burn ward, he said.

Eckstein said two firefighters were on ventilators because of "early indication of swelling of the airway."

Dr. Carl Chudnofsky, chair of clinical emergency medicine at USC's medical school, praised the team that treated the firefighters.

"This could have been horrendous," he said.

California Gov. Gavin Newsom said on Twitter he was "grateful for the brave firefighters and first responders on scene battling these flames tonight."

Terrazas said an on-scene investigation will take several days.

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