LOS ANGELES –  Flash flooding north of Los Angeles sent water and mud flowing into canyons and across roadways Thursday, trapping drivers and closing a stretch of one of the state's main north-south freeways.

The California Highway Patrol reported a 30-mile section of Interstate 5 was blocked by flooding near Fort Tejon, about 75 miles north of downtown Los Angeles.

Drivers stuck in the mud waited for roads to be cleared while thousands more were diverted to alternate routes expected to take four or more hours to traverse through the mountain region in Southern California.

There were no immediate reports of any injuries.

"Due to the drought and fires, all the rain coming down heavily is causing floods," CHP Officer Andrew Mack said. "We have a lot of people up there trapped on the roadway."

The flooding is being caused by a low pressure system bringing rain and severe weather to the region. Flash flood warnings remained in effect early Thursday evening for Los Angeles and Ventura counties.

National Weather Service meteorologist Joe Sirard said as much as 1.45 inches of rainfall was recorded in parts of northern Los Angeles County. The system was expected to slowly drift eastward through Friday.

"We still have the slight chance of showers and thunderstorms in a lot of the areas," he said.

In Lake Hughes, about 40 miles east of Fort Tejon, Los Angeles County Fire Department Capt. Keith Mora said the agency rescued four people and two dogs from atop one car. Many more were able to walk to safety after waiting out the flood on top of their own vehicles, he said.

"They were able to use their vehicles as a security blanket, to stand on top of and stay higher than the flood water," Mora said.