One man was killed and three others were injured at a well site about one mile north of Fort Lupton.
The three people hurt were taken to Northern Colorado Medical Center in Greeley. Their names and conditions are not being released.
A team from the Occupational Safety and Health Administration (OSHA) is investigating the accident.
Weld County farmer Cole McPeek was working at his grandfather's ranch across the street.
"It's real quiet," McPeek said. "The only noise is gravel trucks. Gravel trucks and oil trucks. Nothing usually happens out here."
His calm day quickly turned chaotic when he was a giant plume of natural gas.
"Just big huge white mist," he recalled. "It went up about 150 feet in the air."
The high pressure gas release lasted less than a minute.
"By the time I got back inside, the first sheriff got there," McPeek said. "Then the ambulance and fire department."
SKY 9 video showed mangled equipment at the oil and gas well site owned by Ecana Oil and Gas USA.
"We saw one guy; he was on the ground," McPeek said. "So they had a blanket over him."
The man who died was 60 years old and a contractor working for Ecana, according to spokesperson Wendy Wiedenbeck.
"Anytime we lose a member of our team, it's a very sad day," Wiedenbeck said. "It is a reminder of the work we do every day, and it's also a reminder of how close we are."
Work on the well is suspended as OSHA investigates what went wrong in this quiet corner of Weld County.
Encana is cooperating with federal investigators who were on site much of the day Wednesday.
An OSHA duty officer reached by phone Wednesday told 9NEWS this is an open case and there will be no comment until the investigation is complete.
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