A powerful thunderstorm caused flash flooding, swamped parked cars, downed trees and caught motorists off-guard heading home Tuesday afternoon around rush-hour.

Downtown Albany around Sheridan Avenue and North Pearl Street was deluged.

Zack Sowards of Rotterdam said he got out of work nearby during the downpour that lasted about 45 minutes and saw water rise above the license plates of parked cars on North Pearl.

"The buses were plowing right through it," while a car was pushed by "waves of water" along Sheridan, he said.

Anni Cole watched from her Chapel Street apartment window as Sheridan Avenue — at a spot she said routinely floods in heavy rain — turned into a "raging river" carrying debris, and parked cars lifted off the pavement collided. A video she took showed water forcing its way up through cracks in the sidewalk.

Daniel Hershberg, an engineer and consultant to the Albany Water Board, said that area is a natural low point at the base of the Fox Creek sewer where it joins a larger sewer at North Pearl Street. In a localized downpour, he said, the drainage area exceeds the capacity of the sewer system.

National Weather Service meteorologist said the storm took an unusual path, drifting from the north and was isolated over Latham and Albany where it sat and dropped about 2½ inches of rain over the course of an hour. He said quarter-sized hail was also reported.

The city of Albany opened a shelter at the Myers Middle School. The mayor, police and Red Cross opened at 9:30 100 Elbel Court off Whitehall Road and some people had their electricity shut off when basements flood

The American Red Cross of Northeastern New York Region opened a shelter at the Meyers Middle School at 9:30 p.m. for those were flooded out of their residence or who lost power.

Police Chief Steve Krokoff said an electrical engineer needs to check when power can be restored when basements flood and water gets into electrical panels.

Albany County Comptroller Mike Conners was among those caught in the storm as he drove down Sheridan Avenue. He said he failed to bypass the high water on a side street before passersby pushed his vehicle to higher ground.

David Bushey of Colonie, a parking valet at nearby 677 Prime, said a section of Orange Street between the restaurant and the state Department of Environmental Conservation headquarters on Broadway was flooded.

"A car tried to drive through it and the water came up over the windows," he said. The driver got out and pushed his vehicle to a CDTA bus parking lot, but "when he opened his car doors, all this water came flooding out."

Bushey also said "a huge whirlpool" above an overwhelmed storm drain had debris swirling in circles.

By 7 p.m. much of the high water had drained in the area though not at the Hampton Inn and the parking lot of First Church of Albany. A few hours later, the emergency was over and the streets were navigable but muddy.

In the city's Pine Hills neighborhood, streets flooded and trees were toppled, including one that landed on a house on the corner of Western and Milner avenues.

The performance of "Smokey Joe's Cafe" at the Capital Rep theater was canceled as was the Park Playhouse performance of "Oliver" in Washington Park. The Price Chopper on Delaware Avenue closed after its roof collapsed.

In Colonie, traffic on the Northway was snarled. A downed tree blocked at least one lane near Exit 6. Traffic was detoured when Kunker Road at Route 9 flooded. At the Times Union, one of two stately blue spruces was uprooted at the employees' entrance. A few years ago, another spruce at that site was downed in a storm.

Meanwhile, 10 miles west in Schenectady, there was virtually no trace of the storm and many residents were initially unaware of what happened in Albany County.