A man was assaulted in Duston, Northampton, after disturbing four men who were acting suspiciously on Tuesday, 1 September.
The 39-year-old man saw the men acting suspiciously at a neighbouring property and challenged them. As he returned to his house he was struck on the head from behind, leaving him with a head wound.
The four offenders are believed to have made off in a car after the incident, which took place in Weggs Farm Road.
Police officers found the patio door of the house the men were seen acting suspiciously near had been opened but nothing is believed to have been taken from the house.
Two of the offenders were white. The first was 23 to 24, about 5ft 11ins and of stocky build. He had slicked back black hair and wore a black leather jacket with a high collar and blue shoes. The second offender was aged 24 to 28, about 5ft 10ins and also of stocky build with short dark hair and stubble. He wore a grey jumper with writing on the front and blue shoes.
The third offender was a darker skinned white man and wore a black padded jacket and blue jeans.
The fourth offender wore a light coloured coat and blue jeans.
Police would like to speak to anyone who may have witnessed this incident, which took place between 3.30pm and 3.50pm, or anyone who has any information regarding it.
Witnesses or anyone with information about this incident is asked to contact police on 101 or Crimestoppers anonymously on 0800 555 111.