No one was injured after a residential structure fire broke out early Saturday morning northwest of Boulder, according to a news release from the Boulder County Sheriff’s Office.

The Boulder County Communications Center received a call about 4 a.m. of a structure fire in the 700 block of Bow Mountain Road. First responders found visible flames and worked to extinguish the fire, which had engulfed the house’s attic.

No other structures were threatened, and all occupants were out of the building when agencies arrived. The cause of the fire is under investigation by the Multi-Agency Fire Investigation Team.

BCSO, Boulder Rural Fire Rescue, Boulder Mountain Fire, Lefthand Fire, Boulder Emergency Squad, Sunshine Fire and American Medical Response all responded to the incident.