He had returned to Braintree Police Station in the early hours of this morning, Thursday December 22, after being on duty at the scene of a fatal house fire in the town.
He came across an injured 32-year-old man outside the station in Blyths Meadow.
While he was making enquiries, two men attacked him.
Other officers were called to help and arrested three men in the local area. One of the officers was assaulted by one of the suspects.
The victim was taken to hospital with a head injury and has since been discharged. Both police officers who were assaulted were taken to hospital with minor injuries.
A 37-year-old man from Braintree was arrested on suspicion of assaulting a police officer and possession of an offensive weapon.
A 42-year-old man from Braintree was arrested on suspicion of assaulting a police officer.
And a 32-year-old man of no fixed address was arrested on suspicion of assaulting a police officer, assault, breaching a court order and failing to answer bail.
All are currently in custody for questioning.