One worker died as a fire broke out at an oil and gas site in Weld County on Wednesday.

Firefighters were called about 6:30 p.m. to a site near county roads 66 and 23, said Fire Chief Kris Kazian of Windsor Severance Fire Rescue.

When firefighters arrived, flames were rising from the top of an oil tank, Kazian said. A work truck was in the area, but no one was with the truck.

Firefighters accessed the top of the oil tank and found a man who was unresponsive, Kazian said. The man was pronounced dead at the scene by the coroner’s office.

Windsor Severance firefighters — along with firefighters from Greeley, Eaton and Front Range Fire Rescue — used foam to suppress the fire, extinguishing it about 10 p.m., Kazian said.

More than 40 firefighters battled the fire east of Windsor.

The cause of the fire, on a Great Western Oil & Gas Co. site, is under investigation. The victim was not identified Wednesday night.

Susan Fakharzadeh, a Great Western spokeswoman, confirmed that victim works for the Denver-based company.

“We’re heart broken to learn it’s a member of our team,” Fakharzadeh said. “This is just tough for all of us.”

Fakharzadeh said the man’s family has been notified. She did not identify him, saying the family has asked for privacy “in this very difficult time.”