(CHICAGO) — Autopsies have revealed the causes of death for two Chicago firefighters who died while responding to fires on the Far South and Near North Sides this week, the Cook County medical examiner’s office said.

Jermaine Pelt, 49, died early Tuesday while working to put out an extra-alarm fire in the 12000 block of South Wallace Avenue.

The autopsy released Wednesday determined he died of carbon monoxide toxicity from inhalation of smoke and soot, the medical examiner’s office said.

Pelt joined the Chicago Fire Department in 2005 and was based on the South Side his entire career, Chicago Fire Commissioner Annette Nance-Holt said.

Pelt’s father, John Pelt, said his son had a proud moment in November when he walked his 28-year-old daughter down the aisle.

The newlywed had delayed her honeymoon and was about to leave town for Jamaica when tragedy struck, he said.

“I would call him a hero. He’s my hero,” John Pelt said. “Right now I’m not feeling that great.”

Just a day after Pelt’s death, a Chicago Fire Department lieutenant died battling an extra-alarm blaze in a high-rise building in the Gold Coast neighborhood.

Lt. Jan Tchoryk collapsed in an 11th-floor stairwell while making his way to a fire on the 27th floor of an apartment building in the 1200 block of North Lake Shore Drive, according to fire officials. His cause of death was determined to be hypertensive-arteriosclerotic cardiovascular disease, according to the medical examiner’s office.

Tchoryk was an outdoorsman and a Navy veteran who served in Desert Storm, Nance-Holt said. Tchoryk had a big family that included a son who recently joined the Chicago Police Department.

Mayor Lori Lightfoot on Wednesday called the back-to-back tragedies “unprecedented.”