Rescue crews responded about 4:15 a.m. to a call of a person in the water near the Franklin Street Bridge, Chicago Fire Department Deputy District Chief Ron Dorneker said at the scene.

When responding officers arrived at the scene there were two people in the water and they were able to throw a life preserver to one man on the surface, Dorneker said. He declined medical treatment and told fire officials that he had gone into the water to assist his friend.

“He told the fire department that he couldn’t see his friend anymore,” Dorneker said. “He believed his friend had drowned.”

Divers went into the water and, after a few minutes of searching in “very limited, almost zero visibility,” they located the second man at depths of about 20 feet, Dorneker said.

Paramedics worked to resuscitate him for several minutes at the scene before taking the man to Northwestern Memorial Hosptial, where he was pronounced dead at 5:17 a.m., according to fire officials and the Cook County medical examiner’s office.

He was identified as 19-year-old Ali Ahsan of the 6900 block of North Kedzie, authorities said. An autopsy on Sunday found that he drowned and ruled his death an accident.

Police did not have information on how he ended up in the water.