The National Transportation Safety Board said the Tesla Semi truck fire in Northern California required 50,000 gallons of water to extinguish.

Washington — California firefighters had to douse a flaming battery in a Tesla Semi truck with about 50,000 gallons of water after a crash, the National Transportation Safety Board said Thursday.

In addition to the massive amount of water, firefighters used an aircraft to drop fire-retardant materials on the “immediate vicinity” of the electric truck as a precaution, the agency said in a preliminary report.

Firefighters previously said the battery’s temperature reached 1,000 degrees Fahrenheit as it caught fire.

The National Transportation Safety Board sent investigators to the scene of the Aug. 19 crash on Interstate 80 near Emigrant Gap, about 70 miles northeast of Sacramento. The agency said it would look into the fire risk from the truck’s large lithium-ion battery.

The agency also found that the truck was not operating one of Tesla’s partially automated driving systems at the time of the crash, according to the report. According to the agency, the systems were not operational and “could not be operated.”

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The accident happened around 3:13 a.m. when a Tesla employee was driving a tractor-trailer from Livermore, California, to a Tesla facility in Sparks, Nevada. The report says the truck went off the road while making a right turn and struck a tree. It then went down a slope and came to rest between several trees. The driver was not injured.

After the accident, the truck’s lithium-ion battery caught fire. Firefighters used water to extinguish the flames and keep the batteries cool. The highway was closed for about 15 hours as firefighters made sure the batteries were cool enough to recover the truck.

Authorities took the truck to an open facility and monitored it for 24 hours. The battery did not ignite again.

The National Transportation Safety Board said all aspects of the accident are under investigation to determine the cause. The agency added that it intends to issue safety recommendations to prevent similar accidents from happening again.

A message was left Thursday seeking comment from Tesla, which is based in Austin, Texas.

After an investigation that concluded in 2021, the National Transportation Safety Board determined that high-voltage electric vehicle battery fires pose risks to first responders and that guidance from manufacturers on how to handle them was inadequate.

The agency, which has no enforcement powers and can only make recommendations, called on manufacturers to write vehicle-specific response guides to combat battery fires and reduce the risk of pyrochemical leaks and re-ignition. The agency said the guidelines should also include information on how to safely store vehicles with damaged lithium-ion batteries.

Tesla will begin delivering electric trucks in December 2022, more than three years after CEO Elon Musk said his company would start making the trucks. Musk said the electric truck will be able to travel 500 miles per charge while hauling an 82,000-pound load.