A burning truck’s fuel tank exploded on Thursday while Los Angeles firefighters were trying to battle the blaze, injuring nine of them, including two critically, authorities said. All nine were rushed to Harbor-UCLA medical center and were stabilized, said Dr Molly Dean, a trauma surgeon. One of the critical patients had to be intubated and was transferred to a burn unit at Los Angeles General medical center. Of the other injured, four suffered moderate injuries and three had minor injuries, said Captain Erik Scott, a fire spokesperson. “Essentially, we had a mass casualty incident, tragically, of or own members,” Scott said. “The vehicle was the tractor portion of a big rig and was fueled by compressed natural gas carried in two 100-gallon [378-liter] tanks, one of which exploded.” “That explosion was significant,” he said. “The ball of flame was as high as these telephone poles, and it actually did explode one of the transformers nearby.” The truck was completely destroyed, and firefighters stayed well back as a small flame continued to burn in the mangled wreckage, the helicopter footage showed. Scott said the second fuel tank was “still off-gassing and therefore there’s a minor threat”. The driver had stepped away from the truck to call 911 and was not injured. After the explosion, some 160 firefighters responded. The blast occurred adjacent to an industrial area separated from a neighborhood by a wide street and a rail line. Wilmington is 18 miles (29km) south of downtown, near the ports of Los Angeles and Long Beach.