A driver escaped unhurt after an object was thrown at the lorry he was travelling in during the early hours.
The vehicle was travelling eastbound on the A14 between Junctions 10 and 11 at about 2.20am on Thursday (August 23) when the incident happened.
While passing under a bridge an offender or offenders threw an object onto the lorry causing damage to the roof.
The victim stopped at a nearby shell Garage and was not hurt.
A police spokesman said: “Given the severity of what could potentially have occurred, officers are keen to speak to anyone who may have witnessed objects being thrown at passing traffic or the people who were involved.
“Officers are also reminding people of the extreme dangers of throwing objects at moving traffic.”
Witnesses to this incident, or anyone with information about it, can call Northamptonshire Police on 101 or information can be given anonymously to Crimestoppers on 0800 555111.