A man is in a life threatening condition in hospital, following an attack in Basildon at around 7pm on Friday.
The victim, who is in his 40s, and a woman, were reported to have been approached by a man, near Market Pavement. The suspect assaulted the victim, by kicking him once to the head.
The suspect, who was described as white and between 20 and 30 years old then left the scene. He was said to have mousey brown hair, and was wearing a grey t-shirt and jeans.
No weapons were seen and this is believed to be an isolated incident.
The man was taken to hospital and remains in a life threatening condition.
Detectives are appealing for anyone with information to come forward, as they believe there were a number of witnesses near the immediate area at the time.
Anyone who has information can contact Basildon CID on 101 or Crimestoppers anonymously on 0800 555 111.