Joliet firefighters are working to extinguish a fire that started Thursday afternoon at a commercial building on the corner of Eastern Avenue and Washington Street.

The Joliet Fire Department responded to a report of a structure fire at about 2:19 p.m. Thursday, with people possibly trapped, at 1 S. Eastern Ave., the fire department said.

Company 1 arrived to find a one-story brick commercial structure with heavy smoke showing, the fire department said. Crews reported that all people were out of the building.

[ PHOTOS: Building fire downtown Joliet ]

The alarm was upgraded to a box and 2-11 alarm. A defensive attack began after fire broke through the roof, fully engulfing the structure and causing a partial collapse, the fire department said.

The fire is actively burning as of 4:30 p.m.

Fire crews from stations 1, 3, 4, 5, and 6 are currently operating on the scene.

The fire has led to traffic lane closures, according to the Joliet Police Department.

This is a developing story. Check back for updates.