An explosion Saturday at a hash oil manufacturer in downtown Los Angeles injured 11 firefighters.
Three were listed as critical but all were expected to survive.
Los Angeles Fire Department Capt. Erik Scott said ``one significant explosion'' shook the neighbourhood around 6:30 p.m. Saturday.
Firefighters inside the building and on the roof ran for their lives as flames shot out the building and scorched a fire truck across the street.
Some firefighters tore off their protective coats after they caught fire.
Scott described the business where the explosion occurred as a maker of ``butane honey oil.''
Butane, an odourless gas that easily ignites, is used to extractthe chemical THC from cannabis to create a highly potent oil.