Today at my software-development job I learned that if an active shooter in your building is throwing grenades you should hit the ground flat, but if he's shooting bullets you should instead crouch down, because grenade shrapnel goes up but bullets ricochet off the floor. Who knew? (Cover is also recommended if available, of course.)
No, nothing happened -- it's just a little farther afield than our usual mandatory training. I also took a refresher on time-reporting. That was much less interesting.