MEAD — One worker was killed and two were seriously injured Thursday when a frozen, high-pressure water line ruptured at a Weld County oil well site.

The workers were trying to thaw the line when the accident occurred, officials said.

The Anadarko Petroleum Corp. well was being hydraulically fractured, or fracked, by the Halliburton Co., and the workers were Halliburton employees.

Anadarko said it was suspending all fracking operations in the area pending a review of the accident.

The area has been the scene of drilling since at least 1979, but this year Anadarko has sunk at least nine deep horizontal wells, according to state records.

Each of those wells has to be fracked by pumping a mixture of water, sand and trace chemicals into the well at high pressure to crack rock and release oil.

Thomas Sedlmayr, 48, was flown to Denver Health, and Grant Casey, 28, was taken by ambulance to the Medical Center of the Rockies in Loveland. The name of the dead worker had not been released.

“This is a very difficult time for all of us at Halliburton, and we are working with local authorities as they look into the details of this incident,” Halliburton said in a statement.

“Out of respect for the families’ privacy, we are not releasing any additional information at this time,” Houston-based Halliburton said.

Weld County Sheriff’s Office deputies are investigating.

The death and injuries appeared to be caused by a high-pressure water valve that ruptured, said agency spokesman Sean Standridge, the office’s spokesman

Firefighters also responded to the accident.

The incident occurred at 9:30 a.m. at the site off of Weld County Road 9½ just north of Colorado 66.

The workers were trying to warm the pipe, which had frozen, when it ruptured, Standridge said.

The temperature was about 10 degrees at the time, but overnight temperatures were well below zero.

The water pressure was estimated at between 2,500 and 3,500 pounds per square inch.

Dozens of people work at the site, which is about 200 yards long.

Investigators with the federal Occupational Safety & Health Administration in Denver were notified of the accident at about 11:30 a.m. Thursday, said Herb Gibson, OSHA area director.

Two investigators are at the Mead area site looking into the accident, Gibson said.

“It’s a dangerous industry,” Gibson said. “This is a tragic situation.”

The oil and gas industry in 2012 had a fatality rate of about 25 per 100,000 workers — higher than construction, manufacturing, or agriculture, according to the U.S. Department of Labor.

Between 2007 and 2011 there were 19 oil and gas field fatalities in Colorado, according to federal data.

In 2012, a 60-year-old worker died in another Weld County drilling accident that occurred when pressurized gas was released as workers prepared an Encana Corp. Davis well pad to begin pumping.

In October a worker was killed on a drilling rig in Garfield County.

Jesse Paul: 303-954-1733, jpaul@ denverpost.com or twitter.com/JesseAPaul