Juan Bucio, 46, was part of a crew trying to rescue a 28-year-old man who fell off a boat and into the river near Ashland Avenue around 8 p.m. Monday.
While searching for the man, CFD officials said communication was lost and Bucio was gone.
"They were searching for a person or persons in the water. An order was given to switch out divers to bring the second team in, give them a break. At that time they were coming towards the boat. His partner turned around and he was missing. (It was) that quick," Chicago Fire Commissioner Jose Santiago said.
Once divers found Bucio, he was rushed with a police escort to Stroger Hospital, where he was pronounced dead. A procession then led his body from the hospital to the Cook County Medical Examiner's Office.
Bucio was a 15-year veteran of the Chicago Fire Department. He spent the last 11 years on the dive team. He is survived by his wife and two young sons.
Condolences were extended to his family and friends on social media:
The entire Chicago Fire Department's prayers go out to the family of Firefighter Juan Bucio who tragically passed away answering a call of a person in the water near 2600 S. Ashland.— Chicago Fire Media (@CFDMedia) May 29, 2018
A piece of Chicago was lost tonight - a hero who dedicated and ultimately gave his life attempting to save others. On behalf of the entire Police Department, our deepest sympathies for our brothers & sisters at the Chicago Fire Department and the family of fallen CFD diver. -ETJ pic.twitter.com/REkSZg6XXV— Chicago Police (@Chicago_Police) May 29, 2018
OEMC extends our sincere condolences to the family, friends and colleagues of the CFD Marine Unit Diver who succumbed to injuries he suffered in the line of duty tonight while answering the call to help another.— Chicago OEMC (@ChicagoOEMC) May 29, 2018
We will never forget your courage and sacrifice to our city. pic.twitter.com/rY2XK7acWu
Two other members of the dive team suffered minor injuries and were treated and released from the hospital.
The boater is still missing. The search for him will resume Tuesday morning.