A two-car crash has partially blocked the A133 between Clacton and Frating.
Emergency services were called shortly before 4pm to the collision involving a blue Vauxhall Corsa and a black Audi A4.
An ambulance, rapid response vehicle and the East Anglian Air Ambulance are on scene.
Paramedics are treating an elderly man, who is being cut free from his vehicle by firefighters, for head injuries. However the casualty is conscious and his injuries are not thought to be life-threatening.