A FIVE-year-old boy was airlifted to hospital with a serious head injury following a "horrific" crash in Maldon. 
The crash happened on Limebrook Way at about 12.30pm, and involved a black Mini and a black Vauxhall Mokka. 
The father and son in the Mokka were both injured- the boy was airlifted to the Royal London Hospital with head injuries which were initially considered life-threatening. 
The father was taken to Broomfield Hospital, but his injuries are not known. 
Police said a mother and daughter were in the Mini. The driver, 25, was airlifted to Addenbrookes Hospital in Cambridge with a broken leg. 
The other woman was taken to Broomfield Hospital with less serious injuries.
The East of England Ambulance Service sent three ambulance crews, a rapid response vehicle, Essex Air Ambulance and Herts Air Ambulance. 
The road was closed until about 5pm. 
Officers on scene were aware that some drivers, who were likely to have witnessed the crash, may have continued on with their journeys and not stopped.
A spokesperson for Essex Police said: "We would like to appeal for these people and any other witnesses to contact our Serious Collision Investigation Unit on 101 or email collisionappeal@essex.pnn.police.uk."