Emergency services were sent to a motorway in Essex after a car collided with the central reservation.
The single-vehicle collision happened on the northbound carriageway of the M11 between the junctions for Stansted and Saffron Walden around 2.45pm today.
Multiple emergency teams, including an air ambulance, attended.
Firefighters helped free two people who were trapped in the vehicle.
A spokesman for the East of England Ambulance Service said crews treated four patients at the scene, but was unable to confirm their condition.
The trust sent one ambulance, one ambulance officer, one rapid response vehicle, two units from its Hazardous Area Response Team (HART) and the East Anglian Air Ambulance to the scene.
Five fire crews, one each from Stansted, Newport, Harlow, Saffron Walden and Sawston in Cambridgeshire, attended.
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