The driver of a monster truck that careened into a crowd of people in Mexico is charged with manslaughter.

The driver of the monster truck tragedy that occurred last weekend in Chihuahua, Mexico, killing nine people and injuring at least 80, was charged with manslaughter on Tuesday after state prosecutors claimed that 51-year-old Velazquez Samaniego did not meet age and health requirements to be driving the Big Show monster truck, the Associated Press reports. It is not immediately clear what those requirements are.

Samaniego claims that his helmet came off after the initial jump and he hit his head on a metal bar inside the cabin (presumably the roll cage), rendering him unconscious as he careened into the crowd of spectators at the end of the arena. The makeshift arena was built in a park, according to event organizers, and people had gathered without permission in the pit area. According to the report, however, veteran monster truck show organizers have stated that spectators should never have been allowed to be as close to an arena unprotected as they were at Chihuahua show.