By Lauren Victory

CHICAGO (CBS) — A cancer survivor was shot and killed while standing up for a bicyclist, after a hit-and-run collision during a late night ride in the Greater Grand Crossing neighborhood.

Alberto Bocanegra went live on Facebook while driving behind a group of cyclists on a late night ride. Police said the 39-year-old man was driving near 76th and Champlain around 1:30 a.m. Tuesday, when he saw a car hit a 30-year-old woman on her bike, and then flee the scene.

Police said Bocanegra caught up with hit-and-run driver, and got into an argument with the people in that car. Those people apparently called a third driver, who pulled up in a blue SUV and shot the man twice in the neck.

“I tried to stop them, and calm it down. It looked like everybody was calming down, and then the guy with the gun killed the guy in the car,” said one of the bicyclists, who asked to remain anonymous. “It was calm. They were calming down, but because he had a gun, he just had it as though he, in his mind, he was like, ‘Oh, forget it. I’m just gonna follow through.”

Bocanegra was taken to the University of Chicago trauma center, where he was pronounced dead.

Cyclists who were with the victim before the shooting said he was a cancer survivor.

Bocanegra’s lawyer said he had he had a heart of gold, and was very brave. He said it was not unlike Bocanegra to get involved in situations to help other people.

The woman who was struck by the car was in good condition at Northwestern Memorial Hospital with a shoulder injury.

No one was in custody Tuesday morning. Area South detectives were investigating.