A man was punched in the face by two men during a night-time attack in Sudbury.
The victim was hit after being approached by the pair in Friars Street at 10pm on Monday.
He then flagged down a police car and told the officer what had happened.
Police searched the area and deployed the force helicopter but the attackers could not be found.
A spokeswoman for Suffolk Police said officers were appealing for any information in connection with the assault, which took place close to a path leading to the meadows.
“There were two men, but we only have a description of one,” she said.
“He was white, around 5ft 10in tall and aged between 25 and 30. He was wearing a grey hooded top and grey tracksuit bottoms.”
Anyone with information should call police on 101.