An explosion at an EnCana natural gas pumping station injured one employee Sunday near Dacono and southwest of Fort Lupton.
Weld County Sheriff's spokeswoman Margie Martinez said the gas line feeding the station was shut down and the fire was burning itself out.
The employee, who works for Hanover, was airlifted to Northern Colorado Medical Center in Greeley with burns on his hands, face and chest.
Martinez said the cause of the explosion was unknown.
It occurred as the employee was bleeding off a pipeline.
Fire Chief Phil Tiffany says people and livestock within one mile of the fire were evacuated, but were allowed to return mid-afternoon after the fire was under control.
He says investigators are still trying to figure out what happened.
Some witnesses reported hearing an explosion while others said there was none.
There was no estimate of damages.