The cause of the blaze that displaced 26 people and forced the evacuation of 12 apartment units Monday remained under investigation Thursday, according to City of Colorado Springs communications officials.

The single-alarm fire at the Shannon Glen Apartments, 260 N. Murray Blvd., started in the bedroom area of a single apartment and was contained to one unit, but 11 other apartments sustained smoke and water damage, said city spokeswoman Kim Melchor.

Fire and city officials did not say when the cause for the blaze would be determined.

Two people were treated for minor smoke exposure at the scene and at least one person had to be rescued from a third-floor apartment, according to fire officials.

Colorado Springs fire investigators estimated the blaze caused more than $400,000 in property and content damage, Melchor said.

More than 50 firefighters and numerous pieces of equipment, including engines, hazmat, heavy rescue and support personnel, battled the fire.