From CPD's FB:

"Earlier this morning, at approximately 9:45 a.m., an off-duty Chicago Police Officer was driving on the 3500 block of North Damen Ave when he observed a female motorist open her car door in the path of a 21 year old male cyclist. The cyclist collided with the car door with significant force, causing a laceration to his neck. The officer immediately stopped to render aid and, seeing that the victim was losing a large amount of blood from his wound, was able to utilize his specialized training to apply pressure to the cyclist’s neck with a bandage and stemmed the bleeding until Chicago Fire Department personnel could arrive on scene. The injured cyclist was subsequently taken to Illinois Masonic Hospital, where he is currently listed in serious but stable condition. The traffic crash remains under investigation."