The fire was reported around 12:20 p.m. near 1300 South Parker Road at the Club Valencia condominiums.
South Metro Fire Rescue said crews worked to rescue people who were not able to evacuate the building safely.
“Multiple rescues of trapped residents have been made,” South Metro said.
SMFR said 15 people were evaluated by paramedics for injuries at the scene and three were taken to the hospital with minor injuries.
The cause of the fire is under investigation. The American Red Cross of Colorado and Wyoming said it was on the scene to help people who were displaced.