DENVER — An accident at a fracking site in Colorado killed one worker and seriously injured two on Thursday as they tried to thaw a high-pressure water line that had frozen in record-breaking cold conditions, the local fire department said.

Mountain View Fire Rescue said one person was pronounced dead at the scene, while one was taken to the hospital by helicopter and another by ambulance after the incident near the small town of Mead in Weld County, about 30 miles north of Denver.

“What is known at this time is that a high pressured water line ruptured, resulting in the injuries and fatality,” the fire department said in a statement.

It said the cause of the rupture is being investigated.

Denver has been locked in deep-freeze conditions since Monday, with temperatures dropping to well below zero Fahrenheit at night.

Anadarko Petroleum Corp. said the accident took place at one of its locations during fracking operations being carried out by Halliburton Co.

“This tragic accident, associated injuries and contractor’s loss of life has left us all shaken and heartbroken,” Anadarko said in a statement.

It said it has suspended activities in the area and will cooperate fully with the authorities.

Halliburton did not immediately respond to a request for comment.

In addition to Mountain View Fire Rescue, the Weld County Sheriff’s Office and Coroner’s Office are among the authorities investigating the incident, the fire department said.