By Tara Molina

CHICAGO (CBS) — A horrible attack, sparked by a paper bag.

Fast food trash led to a punch that is difficult to watch. CBS 2’s Tara Molina reports from Edgewater where police are on the hunt for that guy who knocked out a senior citizen on a bike.

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That’s how it starts. A man drops a bag out of his car and into the street. The biker pulls up and puts the bag back on the car and that’s when it gets ugly.

Kenmore and Hollywood. It’s where it all started Wednesday afternoon, just after 2:30. On surveillance video, a grey Audi stopped in the intersection. A bag dropped out of the passenger side window. A person walks through traffic with a stroller followed by a man on a bike, who picks the bag up and puts it on the hood of the Audi.

That’s when the passenger opens the door, walks towards the bicyclist and throws a punch, knocking him and his bike down in the middle of the road. He then gets back in the Audi that turns to get away.

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It’s too disturbing to show, but that’s when the driver of the dark Jeep Cherokee, in the right lane, tries to move around the altercation, instead running over the biker with the Jeep’s back tire. His helmet crushed.

According to investigators, the 69-year-old man who was hit and then run over was rushed to Illinois Masonic Hospital, where he was able to tell Chicago Police officers everything he remembered, with his memory jumping from that car door opening to lying in the street, bleeding.

The man who punched him and the driver of the Jeep both left the intersection and left him there. Police are working to track down both right now, calling this aggravated battery of a senior citizen.

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CBS 2 has learned that man’s helmet made all the difference and he is doing ok as of Friday. Still, no one is in custody.

Tara Molina