One person was killed and thousands were stranded Sunday after fierce storms soaked Southern California causing flooding and mudslides.

CBS Los Angeles noted that San Bernardino County Fire spokesman Chris Prater said the body of the deceased was discovered in a vehicle in a rain-swollen Mount Baldy creek.

The storms that hit approximately 50 miles northeast of Los Angeles turned roadways into bodies of water, submerged cars and left behind tons muck and debris.

According to the Los Angeles Times, several people had to be rescued from the flood waters and were treated for hypothermia.

Officials said some 1,500 residents of Oak Glen and 1,000 from Forest Hills lost access in and out of town. In addition, 500 children and their chaperones became stranded at a campground after arriving early on Sunday morning.

The heavy downpours also knocked out power in a few areas.

The National Weather Service said the unusual flash-flooding warnings in Southern California will remain in effect until Monday morning.