A motorist was killed in Calvert County Monday evening in a collision with a rescue vehicle, authorities said.

A Calvert Medic unit was responding to a call when the collision occurred on Route 4 near Sixes Road, county sheriff Mike Evans said in an e-mail message.

He said the medic unit was headed south as the passenger car was turning from Sixes Road to go north on Route 4.

The incident occurred about 4:30 p.m. in the Prince Frederick area.