Excerpts from cbsnewschicago.com:

Two Chicago firefighters were injured at a fire in Ravenswood Wednesday morning. The firefighters were taken to Illinois Masonic Hospital, one with a shoulder injury and the other with a cut to the hand. CFD said both are doing well. 

The fire broke out on the first floor of a two-story building that was under construction, in the 2100 block of North Wilson Avenue. 

No one else was in the building at the time of the fire.

From CFD Media on Twitter:

01:02 Still & Box 2171 W Wilson Still & Box @ 2 stry ord undeer construction 50 x 100 fire on 1st floor, CFD on scene. @ 01:31 struck out the event under the authority of DDC2, All searches clear and negative. 2 FF injured both transported IMMC Green CFD on seen for overhaul

Update Still & Box 2171 N Wilson @ 02:27 Notification Building Department requested at @ 2 stry ord undeer construction 50 x 100, Open and dangerous, Due to fire.

Update 2 FF transported from 2171 Wilson. Both members doing well, both green to Masonic 1 with shoulder injury and 1 with right hand laceration.