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The town of Acton was stunned Thursday by a sudden flash flood brought on by unseasonal monsoonal weather that left vehicles stranded in the street and forced residents from their homes.

Frequent lightning was visible as a strong thunderstorm moved into the area around 4:30 p.m., dumping more than 1.5 inches of rain in just 30 minutes, according to the National Weather Service and Los Angeles County sheriff’s officials.

Temperatures dropped from 93 degrees to 69 degrees within an hour as winds gusted at speeds exceeding 55 miles an hour, the weather service said. Officials also confirmed reports of half-inch hail.

Streets became inundated with sludge, trapping numerous drivers near the area of Syracuse Avenue and Crown Valley Road. L.A. County firefighters performed at least three air rescues for stranded motorists, officials said, but no serious injuries were reported.

The flooding appeared to be affecting several square miles of the town, and rail service between the Via Princessa and Vincent Grade Metrolink stations was halted after the muck blocked the railway. A train carrying hundreds of passengers was stalled and eventually forced to back away and return to the Via Princessa station.

Service was also canceled for Friday for trains 200 and 202  on the Antelope Valley Line that runs between Lancaster and Union Station, Metrolink said, and it was unclear when the route would resume service.

“The first train to operate will be Antelope Valley Line train 204, departing Lancaster at 5:19 a.m. Metrolink will also operate Antelope Valley Line train 285, which makes limited stops between Palmdale and Union Station,” Metrolink said in a news release.

Acton resident Amy Silvia told KTLA she would be unable to stay in her home Thursday night after it was inundated with silt. She wasn’t sure what would become of her kitchen, garage and living room, all coated in mud, but she was mostly glad her animals were safe, she said.

The federal government promotes the saying “Turn Around Don’t Drown” to advise drivers on how to handle flash flooding. If you see a roadway covered in water, turn your vehicle around, away from the flooding.

Just 6 inches of fast-moving flood water can knock you over and possibly carry away your car, according to AAA. If your vehicle does become flooded, leave the car to get to higher and safer ground, prioritizing your personal safety over the fate of your car, AAA says.

KTLA’s Melissa Pamer contributed to this report.