PUEBLO, Colo. -

Firefighters in Pueblo are still putting out hot spots after a two alarm fire destroyed several businesses Tuesday night (6/4/14).

The Pueblo Fire Department says the fire began around 6:40 p.m. at Office Systems Inc., an office supply store, near 3rd Street and Court Street. 

The fire is believed to have started in a shared attic above the business and spread to the rest of the building.

The fire was declared under control two hours after the firefight began, but it is still not out.

At a news conference Wednesday morning, Pueblo Fire Chief Dale Villers said that sections of the building's roof collapsed, landing intact on merchandise and building materials that were on fire. He said those roof sections have prevented water from reaching some of the flames.

The cause of the fire is unknown. No possibilities have been ruled out. Fire investigators have not been able to go into the building because it is not safe to do so. Chief Villers says the structure is not stable.

Firefighters were focusing Wednesday on putting out the flames and keeping the toxic smoke that was being produced by the fire to a minimum.

The Pueblo Workforce Center at 212 W. 3rd Street decided to close for the day Wednesday because of concerns about the smoke.

Office Systems Inc. and Johnson Sport and Ski are confirmed to have been destroyed in the fire.