Emergency workers from three counties are participating in a “mass-casualty” exercise today in North Charleston.

The mock incident simulated an explosion with several people injured at The Farm at Wescott Plantation at Patriot and Wescott boulevards.

The drill started about 10 a.m. and involved police, fire, military and hospital personnel from Charleston, Berkeley and Dorchester counties.

The training for a mass-casualty incident, or MCI, is typical for agencies nationwide under U.S. Department of Homeland Security guidelines.