Two of the country’s largest teacher’s unions are urging school districts to scale back on active shooter drills because they say the drills are traumatizing to students.

Officials say that while the chances of a school shooting are low, they are never zero. There were more than 400 mass shootings in the United States last year, so the fear of a shooting is real to many school officials.

But some teachers are left wondering if shooter drills need to be as intense as they sometimes are. Some schools will conduct drills that realistically simulate a school shooting.

"They've used blanks to simulate the gunshots, they've had a masked person in the hallway, those types of things,” says Metuchen school safety coordinator Bill Ortman. “And I've heard really nothing but bad reactions as to how people have responded to that.”

Ortman says that he still believes that schools should have some version of shooter drills. He says that in Metuchen, drills have become routine – something he says is a good thing.

New Jersey state law is vague on how the drills should be conducted. Some schools can use extreme measures and school officials do not need to tell the students or teachers or parents beforehand.

"I don't think it's one particular thing. I don't think it's that particular drill and having it every month that is going to affect them,” says school psychologist Edith Lima.

Lima has been a school psychologist in New Jersey for about 10 years. She says that drills are OK as long as there is mental health support for the students as well.

"That's why there's such a push now to try to have more mental health support to try to be able to get to those students,” Lima says.

But in a report released this week by gun safety group Everytown and several parent, student and teacher organizations, Melissa Reeves, former president of the National Association of School Psychologists, says, "What these drills can really do is potentially trigger either past trauma or trigger such a significant physiological reaction that it actually ends up scaring the individuals instead of better preparing them to respond in these kinds of situations."

This means that it is up to experts like Ortman to decided how best to conduct the drills.

"Regular rehearsal of both fire, evacuating from the building, and emergency drills, seeking sanctuary within the building, is a good mix to be prepared for just about any scenario that can come up,” he says.

But Ortman does say that he wonders if the state should set parameters for the drills more clearly.

A spokesperson for the New Jersey teacher's union tells News 12 New Jersey that they are concerned about creating drills that could cause trauma to the students.