Officials were predicting “catastrophic flooding” in the coastal towns and warned residents that anyone who ignored the warnings were risking their lives.
At least 10 people were injured within minutes of 130 miles an hour Hurricane Harvey making landfall in the city of Corpus Christi, where up to 40in of rain were expected.
The blast brought down power lines as well as trees and 10 babies were airlifted from the city’s neonatal unit.
The Mayor of the coastal town Rockport, where dozens of people were trapped at a housing centre after the roof collapsed, said: “We’re suggesting that if people are going to stay here, mark their arm with a Sharpie pen with their name and social security number.”
The White House last night confirmed President Trump would visit the region as soon as it was safe for him to do so.
Late on Friday Mr Trump signed a disaster proclamation for the entire Lone Star State, which will immediately release federal aid for the worst affected areas.
Texas Governor Greg Abbott said the state faced “a very major disaster” as he deployed 1,000 National Guardsmen to support the emergency services.
He said as well as the strong winds and storm surges causing major damage, weather experts predicted flooding over the next two to three days “the like of which we have never seen”.
Despite Harvey’s winds being downgraded by the US’s National Hurricane Centre from category four to one, meteorologists warned it “remains life-threatening”.
Coldplay cancelled a concert in Houston just hours before Harvey struck on Friday.
The British band said: “We can’t ask anyone to put their safety at risk. Stay safe and see you soon.”
Images from the International Space Station showed the storm obscuring a vast section of the state’s coast, with its epicentre or “eye” stretching 17 miles.
Harvey is the strongest hurricane to hit the US since 2005, when Hurricane Wilma struck the Florida coast, leaving 87 dead.