Dear Bored,
Let me explain. There is violent crime in this country all the time. Some get completely ignored. Some are covered endlessly. The majority are news for as little as an hour, up to a few days. What makes one story stick around, is the narrative around the story. If it fits with the daily news narrative, it gets more attention. That depends on timing more than anything else. There have been cars panning into crowds in this country dozens of times. The only one that was a major national story, was a famous person whose life had fallen apart. I think it happened around when I was born.
A little tip. If you want to understand how bias figures into what makes the news cycle, look at advertising trends. Not political rhetoric. On that note, whatever the topic is you’ll understand it better if you ignore the partisan yammering.