MEXICO — A training exercise involving all area emergency, first-responder agencies begins at about 3:30 p.m. on Tuesday. Oct. 26, at Mountain Valley Middle School.

Police, fire, ambulance and other agencies will respond to a mock emergency scenario that involves a person with a gun about to enter the school.

The drill was organized to give emergency response personnel a chance to train for such an incident should it occur in the future.

The timing for the “shooter” drill was scheduled to take place after most students had left the school for the day.

Residents are asked not to be concerned when alarms and sirens go off, and numerous emergency vehicles speed near or in town.