A strong storm system battered central and southeast Texas Thursday, bringing heavy rain and causing high water, flash floods, and power outages across the state. The National Weather Service issued a Flash Flood Warning through Thursday afternoon for more than ten counties across Texas. The Texas Department for Public Safety said the four worst affected counties were Williamson, Hays, Comel and Travis in central Texas. Heavy rain triggered flash floods in Austin, Texas' capital city, forcing scores of people from their homes amid evacuation advisories and prompting helicopter rescues, officials said. Some areas surrounding the city were slammed by as much as 15 inches ( 381 mm) of rain, according to Austin-Travis County's Emergency Medical Service. Austin Energy reported as many as 12,000 customers without electric power Thursday morning while a few schools called off classes due to extreme weather conditions. Houston, the largest city of Texas, was also hit hard by the severe storm. Meteorologists said the metropolitan area could see between 1.7 inches (43 mm) and 5 inches (127 mm) of rainfall Thursday morning. The heavy rain swamped portions of several freeways in the Houston area and caused road closures. Some bayous and creeks are near the tops of their banks in the greater Houston area. The Houston Independent School District cancelled all after- school activities due to the weather. Officials from Centerpoint, a major energy delivery company, said more than 5,600 customers throughout the region remained without power by Thursday noon. The Texas Department for Public Safety said there were no firm numbers of damages yet from the storm. No injuries were reported in the storm-hit areas.