Thousands of people in the Houston area faced sweltering heat without power on Saturday following severe storms that claimed at least seven lives, according to local media and the National Weather Service.

The NWS predicted temperatures around 90 degrees and warned residents in a post on the X social media platform of the threat of heat stroke, saying “Don’t overdo yourself” as they continued cleaning up from Thursday night’s storms.

Storms packing winds of up to 100 mph tore through the region, damaging homes and buildings, felling power lines and leaving more than 800,000 people without electricity, according to local media.

A tornado touched down near the suburb of Cypress, shattering trees and windows and strewing debris, local media said.

As of Saturday morning, more than 500,000 people in the region still were without power, according to PowerOutage.us, a website that aggregates electricity outage data from utilities across the United States.

President Joe Biden on Friday issued a major disaster declaration for seven Texas counties, making residents and businesses eligible for federal assistance.