Two Los Angeles firefighters were critically injured and several others hurt in an explosion early Thursday in Wilmington as they were trying to extinguish a fire on a truck with pressurized tanks, authorities said.

Firefighters responded to a vehicle fire shortly before 7 a.m. at 1120 N. Alameda St. in Wilmington, according to an emergency alert from the Los Angeles Fire Department. They were trying to put out the fire on a the truck when the explosion occurred.

Investigators are still trying to determine if the truck was powered by compressed natural gas or was transporting the tanks in the trailer bed, LAFD spokesperson Nicholas Prange said.

At least seven firefighters were transported to Harbor-UCLA Medical Center, with two reported to be in critical condition, the LAFD said.

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This is a developing story.