SAN DIEGO — An Amazon semi-truck flipped on its side during an unexpected rain shower early Sunday, shutting down part of Interstate 15 for hours while a Hazmat crew dealt with a fuel leak.

The crash happened around midnight on northbound I-15 near Interstate 8 in the Kensington area, according to California Highway Patrol logs. It’s a troubled downhill stretch of freeway for truckers, especially in the rain: Another Amazon big rig was involved in a deadly crash in the area during a March rainstorm.

It wasn’t immediately clear what caused the driver to lose control in Sunday’s crash, but the big rig crushed part of a guard rail and came to a rest on its side, extending off the freeway, video from OnScene TV showed.

Dispatchers sent an ambulance for the driver, according to CHP, but details about the severity of their injuries were not provided. Officials also sent a Hazmat crew to address a propane leak coming from the wrecked tractor-trailer.

Initially, police blocked all northbound lanes near Adams Avenue, gradually reopening portions of the freeway as the morning went on. Traffic was flowing normally by about 7 a.m., according to Caltrans.