It's a terrifying thought for any parent, what should your child do if an active shooter enters their school?

Schools across Long Island practice active shooter drills to prepare, but they are not all the same.

The goal of the drills is to teach teachers and students how to react if a gunman enters their school.

Don Longo, of Radius Investigations, says he's been hired by half a dozen Long Island schools over the years to teach the run, hide, and fight method.

If running is not an option, Longo teaches how to barricade yourself properly and out of the line of sight through windows or doors.  Lastly, if the gunman enters your space, he says you fight with everything you have.

Meanwhile, Suffolk County Police Commissioner Stuart Cameron says having teachers and students run for their lives could be dangerous and put them directly in harm’s way.  He says if a classroom door is locked, most of the time, a gunman will pass it by.

Lars Clemenson, superintendent of Hampton Bays Schools and president of the Suffolk County School Superintendents Association, says that teachers and staff should immediately go into lockdown.

However, Clemensen says different circumstances call for different actions and a lockdown isn't always enough.

How to make that judgement call, Clemensen says, is now part of the training.