Until last night's tragic accident in Omaha, I can't find a single instance of a "Cops" crew member being shot or killed during production of the program. Considering all the situations they've faced in the 25-year history of the show, that's remarkable.
That's not to say that crew members haven't gotten involved in the action. From Wikipedia:
In one episode, the sound mixer for the camera crew, a former EMT, assisted a police officer in performing CPR.
In another episode in season 11 that took place in 1998 in Atlanta, Cops camera operator Si Davis, who was coincidentally a Las Vegas Reserve Police Officer, had to drop the camera and assist an Atlanta police officer in wrestling a suspect into custody. The APD officer, it turned out, had been severely injured during a foot pursuit; meanwhile, sound mixer Steve Kiger, picked up the camera and continued recording the action which eventually made air. Because the camera crew was dressed in tactical gear, no one noticed that it was the camera operator in front of the camera.
In an episode of season 14 (2001–2002) during the arrest of a man after a car chase in Hillsborough County, Florida, the sound mixer held the sister of the man away from the deputy after she tried to intervene in the arrest of her brother. Also, during the first episode of Season 22, a Las Vegas officer was scuffling with a suspect high on PCP, who eventually tackled the officer and required the camera operator and Las Vegas paramedics to wrestle the suspect off of the officer.
In an episode of season 26 (2013-2014) first broadcast on February 1, 2014, during the arrest of a man in Sacramento, California for battery on his girlfriend, one of the camera crew had to pull one of the suspect's pit bulls away from one of the arresting officers. The dog was biting the officer on the leg after being commanded to do so by the suspect.