The National Transportation Safety Board (NTSB) has adopted a new recommendation to require fire suppression systems in all new school buses—and to retrofit those already in use. The decision is in response to a fatal December 2017 fire in Oakland, Iowa that killed the driver and a 16-year-old student.

The initial recommendation to the National Highway Traffic Safety Administration (NHTSA) limited the equipment to newly manufactured school buses and extended the recommendation to all school bus manufacturers. But the board approved the amendment that the recommendations extend that requirement to retrofitting all existing school buses with fire suppression systems.

NTSB’s investigation concluded that had the Riverside Community School District bus had a fire suppression system installed in the engine compartment, it could have provided additional time for 74-year-old driver Donnie Hendricks and student Megan Klindt to safely evacuate.

NTSB also urged NHTSA to develop a standard to improve the construction of firewalls between school bus engine compartments and the passenger compartment to limit the passage of toxic gases and heat. The investigation concluded that the gases and heat led to the incapacitation of the bus driver and student, which led to their deaths.

“The more time, the better the evacuation will be,” said NTSB investigator Michele Beckjord. “You’re never going to prevent all fires, but what you can do is if the fire does occur, to quickly put it out and to keep it from reflashing.”

NTSB found that about 1.2 school bus fires occur each day.