(OLD COLORADO CITY, Colo.) — The Colorado Springs Fire Department (CSFD) is investigating after a large structure fire broke out in the early morning hours of Friday, Dec. 29 in Old Colorado City.

According to CSFD, firefighters responded to a commercial structure fire at 4 a.m. on Friday on Naegele Road, just north of Highway 24 and 21st Street. CSFD said crews could see large flames when arriving on scene, and they could hear explosions, likely from cars inside the building.

CSFD said a second alarm was called for additional resources, and the fire was deemed under control at 4:49 a.m.

CSFD said investigators responded and are working to determine the origin and cause of the fire.