CHICAGO (CBS) — Even the thought of a shooting at their child’s school is terrifying for parents, but officials in Lake County said they want to make sure they’re prepared should it ever happen, so they were staging an emergency drill in Wadsworth on Friday.

There were no students inside Newport Elementary School on Friday. Instead, it was filled with volunteers and others taking part in the drill.

Several county departments were involved in the active shooter drill, with a total of more than 150 first responders, and more than 200 people helping out.

The scenario called for a person to play the role of a gunman inside the school, as police were called in to eliminate the threat.

Lake County police, firefighters, and school personnel spent more than a year planning the drill, long before Friday morning’s shooting at Northern Arizona University – where a freshman shot and killed one person, and wounded three others – and long before the shooting massacre in Roseburg, Oregon – where a shooter killed nine people before taking his own life in a shootout with police.

Those incidents and more like them were on the minds of those training on how to respond to such an event.

“We have to prepare ourself, and we have to be ready to respond to the events that are occurring as you say – this morning, Oregon – and the question that we continue to ask ourself is not if, but when?” Lake County Undersheriff Raymond Rose said.

Officials said they would review the performance during Friday’s drill, and regroup in about two weeks do discuss what might have gone wrong, what went right, and how they can do better.

“By our doing this today, we’re going through, we may make mistakes today, but we’ll be better prepared in the event that we need to be ready for such an event,” Sheriff Mark Curran said.