Powerful thunderstorms tore through the region tonight, spawning flash floods that stranded motorists, tornado sightings that brought fear of more destruction, and scattered power outages and road closings that affected thousands.

No injuries were reported, but more than 30,000 homes lost electricity.

Tonight's rotating thunderstorms caused numerous sightings of funnel clouds in Allegheny and Westmoreland counties, forecasters said, though there were no confirmed reports that a tornado had touched down.

Flash floods swamped the region. At least 2 to 3 inches of rain was believed to have fallen by 8 p.m. in some locations. At the National Weather Service office in Moon, 3.4 inches of rain was recorded, said meteorologist Richard Kane. Forecasters received reports that 3 inches of rain had fallen in Greensburg in an hour.

The storms prompted officials in Wilkinsburg and Reserve to declare a state of emergency.

High water trapped motorists and shut down many roads. In Allegheny County, the East Busway was flooded; Second Avenue was impassable; the 10th Street bypass was closed; Route 65 near Bellevue was reported flooded; and cars were abandoned in rising waters on Washington Boulevard near Negley Run Road.

Throughout Pittsburgh's East End, streets were transformed into rivers during the heaviest downpours. In neighborhoods including Squirrel Hill, Shadyside and Highland Park, firefighters, emergency crews and passersby rescued a number of motorists from their flooded cars, said Guy Costa, the city's public works director.

On Forbes Avenue, Northumberland Street and Ellsworth Avenue, he said, water, in some cases, approached the tops of cars.

"There were many cars that tried to drive through the pools of water, and they got stranded," Mr. Costa said. "They had to climb onto the roof."

Emergency crews and residents were still tallying the damage.

"We've had flooding, trees down, minor landslides," Mr. Costa said. "We don't have anything major at this point."

Water was more than 3 feet deep as it crossed West Street and into Sarah Carter's driveway in Wilkinsburg, where several residents reported flooded basements.

Patricia Murphy was home with her daughter, Pam Funk, and granddaughter, Kaileen Funk, when rain started falling. Ms. Murphy ran upstairs to close windows, then heard a noise in the basement. When she went down stairs, water was pouring in through a wall.

"My daughter and I worked as fast as we could, but it was just overpowering," she said. The rushing water flipped floor to ceiling cupboards, leaving more than 3 feet of standing water in the basement.

Next door at Trish Drake's house, water was at least 6 feet deep. At 8:55 p.m., she looked at the television and said, "they just keep saying more is coming, more is coming, and we can't handle anymore."

Firefighters in the city and Allegheny County battled several fires brought on by lightning strikes, including to one structure on the South Side.

In Westmoreland County, emergency crews worked to rescue several people from flooded homes in Irwin. Lawrence County dispatchers reported that lightning strikes at several homes had caused fires.

Tonight's storms were spawned in Eastern Ohio where sunshine served to destabilize moist air that had been left behind from a warm front that spread north and east through Pittsburgh during the morning. It brought with it many sightings of funnel clouds, and the weather service issued a tornado warning for parts of Allegheny and Westmoreland counties from about 7 to 7:30 p.m.

The advisory warned of an impending thunderstorm "capable of producing a tornado near Pittsburgh's South Side" and moving east at 15 miles per hour. Locations included in the warning included Downtown, the North Side, Upper St. Clair, Mt. Lebanon, Bridgeville, McKees Rocks, Bethel Park, West Mifflin, Carnegie, Baldwin and Wilkinsburg.

"This storm is capable of producing nickle size hail and destructive straight line winds," the warning said. "Take cover now! If you wait to see or hear it coming it may be too late to get to a safe place."

Emergency dispatchers in Westmoreland County reported a funnel clouding sighting in Jeannette about 8 p.m., which was unconfirmed by the weather service. There also were reports of two possible tornado touchdowns as the first of two lines of thunderstorms crossed Allegheny and Westmoreland counties beginning at 6:15 p.m.

There were no immediate reports of tornado or other wind damage, and the touchdowns reported in the vicinity of North Versailles and Bessemer were not confirmed, forecaster Rich Redmond said.

After the tornado warning expired, a second wave of storms was still crossing the area but was not believed to have any tornadoes associated with it.

The Weather Service extended a flash flood warning for Allegheny County until 1 a.m. and warned of stream flooding and periods of heavy rainfall.

Duquesne Light said 22,400 customers were without electricity as of 10:30 p.m., with the largest concentrations of outages in Monroeville, Penn Hills, Forest Hills, Lawrenceville and Churchill.

Spokesman Joseph Vallarian said "we are still assessing the level of damage and are unable to provide a restoration time."

About 6,811 Allegheny Power customers were without electricity as of 10:30 p.m., with restoration expected as late as 6 p.m. tomorrow.