(CBS) – Weather authorities on Monday night issued an overnight flash flood warning for parts of Cook and DuPage Counties as thunderstorms hit the Chicago region.

The warning was in effect until 3:30 a.m. Tuesday for east central Cook and east central DuPage, the National Weather Service said.

Up to 2 inches of rain had already fallen as of 9:30 p.m. Monday, and another 1 to 2 inches was possible, triggering the flash flooding.

The worst-hit communities could include Chicago, Cicero, Berwyn, Oak Park, Downers Grove, Elmhurst, Lombard, Westmont, Maywood, Villa Park, Brookfield, Franklin Park, Hinsdale, Westchester, LaGrange, Forest Park, River Forest, Summit, Lyons and Burr Ridge. Some interstates were also considered vulnerable.

There were reports of standing water on Lake Shore Drive Monday night.