Severe thunderstorms blew out windows in high-rise buildings, downed trees and knocked out power to hundreds of thousands of homes and businesses in the Houston area Thursday as Southeast Texas got pummeled for the second time this month.

Flash flood and severe thunderstorm warnings were issued for multiple counties, with damaging winds and even tornadoes possible into the evening, said Houston’s National Weather Service office.

“Take shelter now if you’re in the path of this storm. Head to the lowest floor!” the NWS office warned on social media.

Streets were flooded and trees were down across the region. CBS affiliate KHOU-TV showed images of shattered windows on an office building in downtown Houston, with glass littering the street below. Video posted to social media showed a downtown street covered in debris.

Video also appeared to show water being blown into Minute Maid Park, the home of the Houston Astros, despite the stadium’s roof being closed. 

Flights were grounded at Houston’s two major airports because of the weather. Sustained winds topping 60 mph were recorded at Bush Intercontinental Airport.

In total, just over one million customers were without power in Texas as of Thursday evening, according to utility tracker PowerOutage.us.

Of that, more than 842,000 customers were without electricity in and around Harris County, which contains Houston. The county is home to more than 4.7 million people.

“Please avoid the roadways if possible, but if you’re out, please use caution and be on the lookout for debris,” Harris County Sheriff Ed Gonzalez wrote on social media. Gonzalez shared an image of vehicles attempting to traverse around a massive tree that had come crashing down into an intersection.

The Houston Independent School District announced all schools would be closed Friday.   

Heavy storms slammed the region during the first week of May, leading to numerous high-water rescues, including some from the rooftops of flooded homes.