Denver, CO – An explosion in a Westminster apartment building Sunday morning that injured multiple people stemmed from a gas line, Westminster fire officials said Monday.

The explosion at the Lakeview apartments near 3761 W. 68th Ave. injured six people, with three going to the hospital and one person in critical condition, responders said. His condition has since been upgraded.

A man at the scene said his brother was the person in critical condition. Tinkham Mounkeothlakem, 49, was in the laundry room about 10 a.m. As he pressed a button on the dryer, an explosion burned his hair, face and hands, the man said.

Firefighters confirmed that Mounkeothlakem was still in the hospital Monday. He was upgraded to serious condition and moved to University Hospital for burn treatment.

Of the 80 people who live in the building, 21 remain barred from returning home. The building is sound, firefighters said Monday, but gas and power have not been restored yet and windows are still blown out. Red Cross was assisting displaced residents.