From Chicago Fire Department Media on Twitter:

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.

Excerpts from nbcchicago.com:

The city of Chicago was in mourning after a Chicago Fire Department diver died Monday from injuries sustained during a rescue operation.

Juan Bucio, 46, was among the first responders firefighters called to a report of a person missing in the Chicago River near the 2600 block of South Ashland Avenue at around 8 p.m. Monday night. Fire officials said Bucio was searching for a 28-year-old man who witnesses said they saw jump from a boat into the river. At one point, Bucio lost communication with his dive partner during the rescue attempt.

He was later located and CPR was administered before he was taken in critical condition to Stroger Hospital, where he later died.

“An order was given to switch out divers to bring the second team in, give them a break,” Chicago Fire Commissioner Jose Santiago said at a news conference. “At that time, they were coming towards the boat. His partner turned around and he was missing, that quick.”

Bucio joined the fire department in 2003, and has been on the dive team since 2007. He is survived by his two sons, ages seven and nine, and nine siblings, including a brother who works for the Chicago Fire Department, and a sister who works for the Chicago Police Department.

Officials did not locate the missing boater, and a search for him was expected to resume in daylight on Tuesday.

Bucio was the 13th member of the Chicago Fire Department to die in the line of duty since the year 2000.