Every hospital in New Jersey needs to be ready for a mass casualty event.

To be prepared, doctors, nurses and administrators took part in a drill Friday at St. Joseph’s Medical Center in Paterson.

The scenario that staffers trained on involved a train derailment with a chemical spill.

Doctors and nurses had to respond as if it were real.

Some "patients" arrived at the hospital by ambulance. Others had head wounds, complained of dizziness or walked in with lacerations to the arms or face.

Because the simulation involved a chemical spill, there a was another component to deal with before anyone entered the hospital.

“Since they do have some chemical involved, they need a decontamination to happen," said Adam Perper, director of Emergency Preparedness with St. Joseph's Medical Center.

Staffers also had a chance to practice setting up the “decon-tent,” plus dressing in full hazmat gear.

Montclair State nursing school students, who posed as patients, were washed clean of contaminants.

“It’s vital for the hospital to due drills and exercises all year round," said Perper.

“They are people from different floors, different units, departments. They practice on a monthly basis they come for at least four to eight hours once a month.”

Administrators were also in-on the drill. A full Emergency Operations Center was open inside of the hospital.

People from nursing, bedding, risk and safety sat alongside fire and police, with Paterson coordinating a response.

“We’re fortunate we have a drone so we can see in real time all the activities," said Anthony Tesoriero, vice president of facility operations. “We have evaluators from NY Presbyterian and a few other hospitals to evaluate the process.”

The outside evaluators from other hospitals will return a full report on how staffers can improve their response or make corrections for the next drill or the next mass casualty event.