Three people on a film set were critically hurt in an explosion that sparked a grass fire near Los Angeles on Tuesday, authorities said.

The blast was reported around 4:45 p.m. in a mixed use industrial neighborhood of Santa Clarita, said Los Angeles County Sheriff’s Deputy Abraham Bedoyan.

Ambulances took three critical patients to hospitals, according to Supervisor Martin Rangel with the LA County Fire Department.

Fire spread to a grassy hillside but firefighters were able to quickly douse the flames, Rangel said. Aerial TV news footage showed fire crews at a large lot with multiple cargo containers.

Sheriff’s officials advised residents to stay clear of the area about 30 miles (48 kilometers) north of downtown Los Angeles.