Crews across the area were called out for flood rescues.
KING OF PRUSSIA, Pennsylvania (WPVI) -- Flash flooding stranded drivers along the Schuylkill Expressway, one of the region's busiest roads, as storms barreled through late Wednesday night into early Thursday morning.
The remnants of Tropical Depression of Fred brought heavy rain, flooding and tornado warnings.
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Lightning streaked across the sky and claps of thunder probably woke you up from sleep - along with Emergency Alerts on your cellphone and television.
Crews across the area were called out for flood rescues.
The eastbound Schuylkill Expressway was shut down for hours near the Conshohocken Curve due to ponding on the roadway. It started to reopen just before 5 a.m. Thursday when traffic was allowed to get by again.
The heavy downpours caused so much flash flooding along many sections of I-76, near Manayunk, Conshohocken and at the exit for 202 in King of Prussia.
Drivers were trying to move around the water.
Firefighters were walking through the water, checking stranded cars to make sure no one was trapped inside.
Some drivers tried to make it through floodwaters on North Gulph Road in Montgomery County, not far from the Walmart and Wegmans near the King of Prussia Mall.
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Cars became stuck under the I-76 overpass. It was a scary situation for drivers who took their chances.
"I tried to actually make it all the way through, but I didn't. My car stopped. I tried to reverse; it didn't work. So I cut my car off and I had to get out of the car," Sierra Hillanvrand of King of Prussia said.
Hillanvrand told Action News North Gulph Road was like a lake, with the water too deep for her Jeep Cherokee to make it through.
Firefighters walked her out of the flooded area to safety.
Over at First and Clark avenues, also by the KOP Mall, Upper Merion Township police were out there facing a real dilemma.
At one point, cars were trapped in the floodwaters, but rescue crews couldn't go in since a PECO substation was partially submerged.
Drivers are reminded to never try to drive through flooded areas. As the National Weather Service's PSA says: "Turn around, don't drown."