From The Truth About Guns:

Ms. Bull could have written off the message as meaningless trolling, but when she saw that the sender had a gun in his profile picture, she decided to make sure he wasn’t a real-life threat. As it turned out, the sender, named Dylan Jarrell, was from Lawrenceburg, Kentucky – more than 600 miles away from her. Nevertheless, Ms. Bull called the Kentucky State Police and spoke with an officer who took her report very seriously.

With very fortunate timing, police found and stopped Jarrell right as he was pulling out of his driveway with, lo and behold, mountains of evidence that he was about to attack innocent people.