A 38-year-old man and his 13-year-old son were assaulted by men using baseball bats after being pulled from their car in Palmerston North, police say.
Both victims received injuries that required hospital treatment but have since been released. The teenager has a fractured arm.
The incident happened at about 3.15pm on Saturday 25 March near the intersection of Main and Princess Streets.
Their car, a red Holden utility, was badly damaged during the attack and a dog also in the vehicle was beaten with baseball bats.
The attackers left the scene in a black Nissan car.
Several members of the public witnessed the attack and went to help the victims afterward.
Police said they were guaranteeing confidentiality to anyone who witnessed the attack.
Detective Sergeant Grayson Joines said police were sickened that adult men would attack a young person.