Flash flood warning issued in area south of Denver and ground stop in effect at Denver International Airport

There's a flash flood warning in effect in part of Douglas County -- in the Castle Rock area -- and heavy rains are resulting in backups on Interstate 25 in Colorado. A ground stop is also in effect at Denver International Airport.

A thunderstorm was stretched from that area all the way up to the airport in the mid-afternoon on Wednesday. It was bringing hundreds of lightning strikes.

Because of the potential for flooding, Wednesday is a First Alert Weather Day.

The ground stop ordered by the FAA was scheduled to be in effect until 5 p.m.