The massive natural gas explosion ripped through downtown Sun Prairie, about 16 miles outside of Madison.
Officials responded during the dinner hour to reports of a gas leak after a contractor reportedly struck a gas line.
An evacuation of restaurants and homes was underway when the explosion hit and firefighters battled flames for hours afterward.
Authorities identified the firefighter killed as Captain Cory Barr, a ten-year veteran of the department.
“Thank God that our firefighters and those responding were able to get the majority of those people evacuated before the explosion. It could have been a lot worse,” said Lt. Kevin Konopacki of the Sun Prairie Police Department.