Does anyone know what numbers make gun violence national news?

Backstory: My family is in Arkansas and they just texted me to let me know there was a mass shooting with one dead and 24 wounded. Early local news reports say multiple people were shooting into the crowd at a car show.

Question: I was kinda stunned this wasn't on the front page of NY Times or Wapo or Fox? I don't expect it be the very top, but when does a mass shooting actually become national news? What is the criteria?