CHICAGO (STMW) — Thousands of households lost power Wednesday night as a severe thunderstorm rolled through the Chicago region, according to ComEd.

As of 9:35 p.m., Com Ed reported 1,539 customers without power in the city, 4,873 in the western suburbs and 6,447 in the southern suburbs. Edison won’t say how quickly it hopes to restore power.

The slow-moving thunderstorm has already dropped two to three inches of rain across the Chicago area, and is causing flash flooding in Chicago and in near suburbs, the National Weather Service said.

Highways, underpasses and other low-lying areas are at risk of flooding from this storm, the weather service said.

A flash flood warning is in effect until 2:30 a.m. Thursday for east-central Cook County and Lake County in Indiana, the National Weather Service said.

A flood advisory is in effect for the rest of Cook County until at least 11:30 p.m., the weather service said.

The storm could bring quarter-sized hail and 60 mph wind gusts, the weather service said.

Some lanes are closed on area expressways because of standing water, including on the Eisenhower Expressway at Damen Avenue, and on the Dan Ryan Expressway at Roosevelt Road, Illinois State Police said.

Traffic is still moving through those areas but may be delayed, police said. No motorists have been reported stranded or hurt.

Meanwhile, Pink Line trains are stopped at the Damen station because of debris on the tracks, causing “significant delays,” on that line, according to the CTA.

(Source: Sun-Times Media Wire © Chicago Sun-Times 2013. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)