Downtown Tucson will be overrun with first responders Saturday morning during an “active shooter” drill.

Multiple agencies will be involved in the two-hour training session, which begins at 8 a.m. at Pima County Superior Court, 110 W. Congress Street.

The drill will test emergency planning, training and multi-agency operational coordination in the event armed gunmen go on a shooting rampage.

“The drill will provide data for further training to refine how multiple agencies respond to such events and coordinate and communicate with each other,” Mark Evans, a spokesman for Pima County, said in a news release.

“In order to make the drill appear as real as possible, all participants will respond to the drill as if it is actually happening,” Evans said.

Agencies and groups involved in the training exercise are:

— Pima County Superior Court security and administration

— Pima County Sheriff’s Department

— Pima County facilities management

— Pima County Office of Emergency Management

— Tucson Police Department

— Tucson Fire Department

— Southwest Ambulance

— Tucson Office of Emergency Management and Homeland Security

— Tucson 911 communications operators