A Royal Mail post box in Raunds was badly damaged after a small explosive device was placed inside it, causing an explosion.
It is suspected that the device was a firework and the offenders’ motivation may have been to play a prank.
However the explosion could easily have caused serious harm, and officers are appealing for the public’s help to identify those people responsible.
The incident happened at about 7.20pm on Wednesday, October 12, at the junction of Dryden Street and London Road, Raunds.
Officers would like to speak to anyone who may have witnessed the incident, saw anyone acting suspiciously in the area at the time, or has any information regarding it.
Witnesses or anyone with information about this incident can contact police on 101 or Crimestoppers anonymously on 0800 555111.