It's the controversial episode of Glee that featured an eruption of school violence.
The episode that aired Thursday night is being called insensitive by some because it aired so soon after the Newtown, Connecticut school massacre.
"Glee had me terrified tonight" wrote one fan.
A Newtown, Connecticut dad commented, "Those of us with kids that survived the shooting do not need to watch the episode."
The episode showed students being told a gunman was on the loose. Just like Sandy Hook, they locked themselves in a classroom.
A warning slate was put up before the show aired.