Thunderstorms have claimed four lives and caused power outages for nearly a million homes and businesses in southeast Texas.

“We have a storm with 100 mph winds, the equivalent of Hurricane Ike, causing considerable damage downtown,” said Houston Mayor John Whitmire.

Two fatalities were due to fallen trees, and another resulted from a toppled crane.

The storm has now advanced to neighboring Louisiana, prompting flood warnings along the Gulf Coast.

In Houston, traffic lights were out, office windows shattered, and glass littered the streets.

Mayor Whitmire urged residents to stay indoors on Thursday evening.

“Stay at home tonight. Do not go to work tomorrow unless you’re an essential worker.

“Stay home, take care of your children. Our first responders will be working around the clock.”

Flash flood and severe thunderstorm warnings were issued for multiple counties heading into the evening, according to Houston’s National Weather Service office.

The city was dealing with a backlog of emergency calls, primarily concerning gas leaks and downed wires, according to the fire chief.

As of late Thursday night, nearly one million customers in Texas were without power, according to utility tracker PowerOutage.us.

The majority of outages were in Harris County, which includes Houston and is home to over 4.7 million people.

In Louisiana, 215,000 households were without power.

More than 30 million people are at risk of severe weather on Friday across parts of the Gulf Coast.

Last month, another deadly storm struck the city when a tornado in Katy killed one person and injured ten others.