NEW MILFORD - Teachers in Bergen County are learning how to keep their students safe from active shooters.

In a new training aid, teachers are guided through the chilling scenario of what could happen if a gunman enters the school.

The training comes in the form of a DVD called "lockdown" that was produced by the Bergen County Prosecutor's Office and filmed at New Milford High School.

The DVD was given to Bergen County Prosecutor John Molinelli on the same day as the shootings in Newtown, Conn.

Molinelli said he initially wanted to hold the DVD for a while.

"My first reaction was to hold it for a while," Molinelli told News 12 New Jersey. "But then I thought this is something the teachers and law enforcement in Bergen County really need to have"

Teachers already have extensive training on lockdowns.