Definitive proof that a good guy with a gun doesn't always stop a bad guy with a gun

When the shooting started at Marjory Stoneman Douglas High School last Wednesday, there was an armed deputy in the building — someone tasked, specifically, with keeping the students inside safe.

He ran outside when the first shots were fired. And he stayed there for four minutes as the shooter murdered 17 people.

These revelations about the actions — or, more accurately, inaction — of deputy Scot Peterson came on the same day that National Rifle Association CEO Wayne LaPierre spoke in front of the Conservative Political Action Conference, making a by now very familiar argument for guns.

“To stop a bad guy with a gun, it takes a good guy with a gun,” LaPierre said to applause from the CPAC crowd on Thursday morning.

The problem for LaPierre is that this latest shooting in Parkland, Florida, isn’t an affirmation of that view. It’s a direct rebuttal.