News reports what happened. These days people seem to see news organizations as the enemy or at least the news organizations they don't like.
Although one thing I have noticed about news these days is it tends to voice personal opinion openly much more than years ago. Walter Cronkite, Tom Brokaw, Peter Jennings wouldn't spout their own opinion they'd tell you what happened, and that's it.
Show the bodies, name the attackers, send reports to the NRA, government officials don't take no for an answer hound them day and night for a reply. Make it uncomfortable for everyone so much so that everyone wants to prevent another event from occurring.
There is no way to hide what happened or who did it in this age of information. If information lacking people just make up their own story or create conspiracy theories to fill the void.