DENVER (CBS4) – A denver firefighters fell through the floor of a burning home Saturday morning.

Fire crews rushed to the home on West Amherst after reports of a chimney fire. The home was being renovated at the time. They enacted what they call a “fast attack” and went inside.

“They went in, they encountered heavy fire showing, it was through the roof,” Cmdr. Gregory Taft fire with Denver said. “The floor had partially collapsed … as they were proceeding through the interior of the structure one of the officers partially fell through the floor. His crew was able to pull him back out and we were able to continue on with our operations.”

Nobody was inside and the firefighters are okay.

Investigators are trying to figure out what caused the fire.