A 35-year-old Chicago Marathon runner collapsed 500 yards from finish line and died about two hours later, officials said.
The man, a firefighter from Greensboro, North Carolina was identified as William Caviness.
He collapsed near Roosevelt Road and Indiana Avenue where paramedics were able to determine he had a pulse, but he later died, officials said.
"Our hearts go out to his family," said Greensboro Dep. Fire Chief Clarence Hunter.
Authorities suspect Caviness suffered cardiac arrest, but the cause of death was pending autopsy results, according to a spokesman for the Cook County medical examiner's office. He was pronounced dead at 12:03 p.m. at Mercy Hospital and Medical Center, officials said.