Excerpts from cbschicago.com:

Lawrence Matthews died doing what he loved. The dedicated Dolton firefighter collapsed Saturday afternoon while battling a fire in neighboring Harvey.

Matthews went into cardiac arrest and was taken to Ingalls Memorial Hospital, but never regained consciousness, and was pronounced dead at 3:15 p.m.

Chicago and suburban police officers and firefighters saluted the ambulance carrying Matthews’ body in a solemn procession to the Cook County Medical Examiner’s office.

Matthews, 35, was a husband and father of four, who had been with the Dolton Fire Department since 2009.

Dolton firefighters had been called in to assist the Harvey Fire Department on Saturday, after multiple mobile homes caught fire near 150th and Maplewood. Officials said Matthews was on the sidewalk after arriving at the scene when he went into cardiac arrest.

Matthews was a heart transplant recipient who had defied the odds to become a firefighter. Just two years after he received his new heart at the University of Chicago Hospital, Matthews became a firefighter with the blessing of his doctors.

Excerpts from the ChicagoTribune.com:

An autopsy of a Dolton firefighter who died in the line of duty was performed Sunday, but a determination for the cause of his death was still pending, according to the Cook County medical examiner’s office.

Firefighter Lawrence Matthews, 35, of Glenwood, collapsed and went into cardiac arrest after battling a blaze at a mobile home Saturday in Harvey. He was transported to Ingalls Memorial Hospital, and pronounced dead at 3:15 p.m.

Matthews was the recipient of a heart transplant in 2007 at the University of Chicago Hospital. Doctors approved his working as a firefighter after he passed a physical, and in 2009 he was sworn in.

The mobile home near 150th Street and Rockwell Avenue was destroyed in the fire.