Excerpts from CBS.Chicago.com:

 

A Matteson firefighter died Friday afternoon while performing CPR on a shopper at a Walmart in south suburban Matteson.

Mark Zielinski, 49, was “rendering emergency medical aid” to a shopper who needed CPR at the Walmart at 21410 S. Cicero Ave. in Matteson when he died, according to Matteson Fire Chief Chris Schwalbe and the Cook County medical examiner’s office.

He had been with the fire department for thirteen years after spending many years at the Harvey Fire Department, Schwalbe said.