A major highway connecting Los Angeles and Las Vegas has been closed for more than a day, after a truck carrying lithium batteries caught on fire. Now, crews are dealing with a hazmat situation in triple-digit temperatures.

It happened around 10 a.m. Friday, in the northbound lanes of Interstate 15 near Baker, the San Bernardino County Fire Department reported. The truck overturned around mile marker 113, leaking fuel, which then caught fire. Adding to the difficulty, the truck was carrying lithium-ion batteries, which also started to burn.

That's a problem, the SBCFD says, because when lithium-ion batteries catch fire, it "can escalate to thermal runaway, needing massive amounts of water to extinguish."

Both sides of the 15 Freeway were closed near Baker for most of Friday, with the southbound lanes reopening around 3 p.m. As of Saturday afternoon, the northbound lanes remain closed.