LOS ANGELES (AP) — Thunderstorms dumped heavy rain Thursday on mountain and desert areas of Southern California, unleashing flash-flooding and debris flows that stranded vehicles and covered roadways, authorities said.

Numerous vehicles were stranded in Lucerne Valley because of a significant flow of water and debris on State Route 18, the San Bernardino County Fire Department tweeted. No rescues were immediately needed, and crews would monitor the flows, the department added.

Mud and rocks closed Valley of the Falls Drive in San Bernardino National Forest. Yucaipa police tweeted a photo of an SUV up to its hubs in debris.

Jenny Smith, a spokeswoman for Yucaipa police, said a deputy helped rescue an 87-year-old woman from her car, though she said the water and mud were fairly shallow.

A woman whose car also got stuck in the mud was rescued by the fire department, she said.

No injuries have been reported, and Smith said the two vehicles were the only ones that got stuck in the mud on Valley of the Falls Drive.

Warnings for severe thunderstorm and flash-flooding were in effect through the afternoon.

Thunderstorms were brought to the region by monsoonal flow, erupting in the late morning and quickly growing into intense cells with heavy, localized rain, the National Weather Service said.

The moisture was expected to diminish Friday into Saturday, creating only isolated thunderstorms.

The storms followed a record-setting heat wave and shattered some rainfall records this week.

In Campo in southeastern San Diego County, no rain had ever been recorded on a July 11 until this year, when 1.18 inches (30 millimeters) fell, the weather service said. In Palm Springs, Wednesday’s 1.08 inches (27.4 millimeters) of rain destroyed the old record of 0.03 inch (0.76 millimeter) set in 1999.

Along the Southern California coast, meanwhile, the weather service issued advisories for minor coastal flooding during high tides through Saturday.