Some are just rubber necking like anyone else would if they had the chance. That and police officers have each others back when ever possible and that is for the most part a very good thing.
So now my one data point, as some of you may know I was stabbed next to my heart at home one night and I called the cops. Two showed up within a couple of minutes along with an ambulance and arrested the perpetrator (my GF) almost immediately and I lost conciseness and passed out as they arrested her. So four people were there with more coming.
Six months later we went to court and the assistant DA went over the list of people who could testify for the state and there were over 50 cops on the list. It seems that every officer in town and neighboring towns came over to check it out and chat with their buddies. Now this happened at around 1:00 in the morning on a Sunday so you think they would have been out pulling people over for DUI’s but since I live in a very low crime area it must have peaked their interest.
I could see 10 people being needed to investigate the crime and secure the scene, but over 50? Just wow. I do recall talking to the detective in the hospital and him telling me that it was the biggest crime in the last ten years in my town so I guess everyone within police scanner range picked up on it so that they share the story.