De Silvestro was eventually pulled out of the car by the workers. The IndyCar rookie burned her right hand.
On Monday, league officials issued a statement saying workers were forced to use backup bottles to put out the fire and that it would look into why the equipment did not work. All equipment, the statement says, is checked before each race.
At least 14 of 24 safety members are required to attend IndyCar races. At least two trauma doctors, three paramedics and nine firefighters or EMTs must be work race day.