TEXAS CITY — One person died Thursday and four were injured when a sport utility vehicle flipped off Interstate 45 and landed on its roof, authorities and witnesses said.

State troopers closed the northbound lanes of I-45 just north of the Century Boulevard exit shortly after the 4:30 p.m. wreck so they could investigate.

Texas City police Sgt. William Creel said it appeared to be a one-car wreck, which killed one and ejected another. Two medical helicopters carried three people from the scene, and a fourth went by ground ambulance.

“It just started flipping over and over and over and over,” said Sue Smith, who witnessed the wreck.

Sue Smith and her husband, Harroll Smith, were returning to their League City home after hurricane cleanup duty at their Tiki Island house.

The couple stopped and tried to help.

They said the SUV tried to merge from the left to the center lane and could have lost control when it swerved to avoid striking a small, white car that occupied the center lane.

“It was obviously a work crew from all the debris,” Harroll Smith said of the many people restoring Galveston following Hurricane Ike’s destructive storm surge.

“There were two ice chests and food on the ground,” he said. “It was just a real foolish accident.”

One man was ejected 20 feet from the vehicle, he said.

“We called 911, and I could see a guy in the ditch, but I didn’t want to move him,” Smith said.

“They were all unconscious, and we were afraid the gas leaking from the tank would catch fire.”

Harroll Smith estimated the vehicle flipped about 150 feet before coming to rest in the median, partially blocking the inside lane of the feeder road.

Names of the deceased or injured weren’t available, pending notification of family.

Northbound traffic remained at a standstill at 6:30 p.m.