LOS ANGELES (CBSLA) — Twelve firefighters were recovering Sunday after suffering injuries in a fiery explosion in downtown Los Angeles.

The firefighters were taken to County USC Medical Center, where eleven stayed overnight to be treated for injuries ranging from burns to smoke inhalation. Of the injured, four were placed in the intensive burn care unit, and two required use of ventilators. A twelfth firefighter was treated and released Saturday.

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“Most of the burns appear to be toward the upper extremities, to the arms,” said Dr. Marc Eckstein, an LAFD Medical Director. “Some of the firefighters have burns to the back, some have burns to the ears, burns to the hands.”

“We don’t see any evidence of blast injury, which is very very good,” the doctor said. “All the firefighters were awake and alert upon arrival. The ones who were placed on ventilators were done to protect their airway which showed an early degree of swelling.”

As of 9:30 a.m. Sunday, three firefighters were discharged from the hospital, while 8 remain hospitalized, including two in critical but stable condition.

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The fire unfolded just before 6:30 p.m. Saturday in the city’s Toy District.

Responding firefighters from Station 9 were on the roof of the building battling the fire when a commander ordered all to evacuate over concerns related to the smoke emanating. Shortly after, an explosion occurred, injuring the firefighters. A mayday call went out, resulting in more than 200 firefighters from across the city responding.

The site of the fire “appears to be a supplier for those that make butane honey oil,” LAFD Captain Erik Scott said.

Boyd, between Wall and San Pedro streets, will be closed indefinitely while authorities investigate the cause of the fire and explosion. Authorities said residents, employees, and business owners will not be able to access that block until further notice.

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All of the firefighters are expected to survive.