BOULDER, Colo. (KDVR) — Several people were displaced from their homes Friday after an apartment fire that may have been started by a window air unit.

The fire ignited in a first-floor apartment, displacing the person who lives there, according to Boulder Fire Rescue. Several people in nearby units were also displaced because of the smoke.

The American Red Cross of Colorado and Wyoming said the number of displaced was “almost 10.” They found alternative housing through the organization and the apartment’s property management company, according to Boulder Fire Rescue.

Apartment fire contained on Thunderbird Drive

It was reported around 5:30 p.m. Friday on the 4900 block of Thunderbird Drive. Responders found the fire was contained to one apartment unit.

“Because the sprinkler system activated in that apartment, firefighters were able to extinguish the fire quickly,” a Boulder Fire Rescue spokesperson said in a release.

Fire officials think the fire may have begun from a heating and air conditioning unit in the front window of the apartment, but the official cause will be determined once the investigation is over.

Boulder Fire Rescue pointed to the working smoke alarms that helped with a quick response and evacuation.

“We would like to remind community members to please check your smoke alarms on a regular basis to ensure that they are working,” the release states.