Excerpts from Chicago.cbslocal.com:

A blaze at a vacant South Side warehouse that left firefighter Daniel Capuano dead in December was set off by a construction worker using an arc welder that touched off insulation and deemed accidental, the Chicago Fire Department announced Wednesday.

Daniel Capuano, a 15-year veteran of the department, was killed while battling a blaze at a vacant warehouse at 9213 S. Baltimore Av. on Dec. 14.

Capuano, who was assigned to Tower Ladder 34, was searching through heavy smoke on the second floor when he fell down an elevator shaft and into the basement in the three-story warehouse.

The city’s Department of Buildings said after the blaze that unauthorized work was being performed at the warehouse. Work being conducted without a permit included complete removal of the elevator and other structural alterations, spokeswoman Mimi Simon said.

On Dec. 15, building inspectors dropped multiple code violations on the owner of the building and city attorneys moved to have the building torn down.