For the second time this month, severe thunderstorms have pummeled southeastern Texas, claiming the lives of at least four people in Houston.

Windows have been blown out of high-rise buildings, scores of vehicles were submerged, and strong winds and downed trees caused power outages for more than 900,000 customers in the Houston area.

Houston’s mayor, John Whitmire, urged people not go to work Friday unless they are essential, and officials cautioned residents to keep off roads.

The storm system plowed through quickly on Thursday, but flood watches and warnings remained in place Friday for Houston and areas to the east, including eastern Louisiana into central Alabama.

Brutal storms slammed the Houston region during the first week of May, leading to several high-water rescues.