AURORA, Colo. (AP) — Fire swept through a three-story apartment building in suburban Denver early Monday and a 5-year-old boy died after firefighters rescued people unable to escape on their own, officials said.

Fire officials said that people couldn’t get down the stairs of the building during the fire in the city of Aurora and photos showed the outdoor staircases burned in the blaze.

Firefighters using ladders rescued about nine people from the building, said Lt. Dan Pollet, a spokesperson for Aurora Fire Rescue.

The unidentified boy died in a hospital, Aurora Fire Rescue said in a statement.

“Despite the courageous and professional efforts of our members, our community has suffered a tragic loss and the entire Aurora Fire Rescue family is deeply saddened by this incident,” Chief Fernando Gray, Sr. said.

The fire agency said it was investigating the cause of the fire, which was reported at about 1:30 a.m. Police were investigating the death of the boy, said police spokesperson Agent Matthew Longshore.

Officials said more than 30 people were displaced by the fire.

According to the Red Cross of Colorado and Wyoming, the fire directly damaged 12 apartments and left 12 others utility service. It said it was providing lodging assistance and other services to 18 adults and eight children because of the fire.