As police responded to an attack at Ohio State University, school officials blasted an ominous message to students with a set of instructions: "Run hide fight."
It's a mantra that has become standard at many colleges in the event of a shooting. It's meant to tell people near the shooter to run somewhere safe, to hide and to fight as a last resort.
The phrasing was coined in a 2012 video by the city of Houston after the theater shooting in Aurora, Colorado. Many other schools including Georgetown University and New York University have adopted the catchphrase.
But some critics say the concept is flawed and that running or fighting could put someone in greater danger.