Vandals smashed the windscreen of a police van parked outside a church while officers attended a service to welcome a new vicar.
The attack took place at St John's Church in Failsworth, Oldham , some time before 6.55pm on Sunday.
Police described the attack as a 'senseless act of criminal damage' and vowed to 'bring those responsible to justice'.
It took place while a service was being held to welcome the church's new priest, Rev Aysha St Giles.
A post on the GMP Failsworth and Hollinwood Facebook page read: "Senseless Criminal Damage.
"Officers from Failsworth Neighbourhood Team attended at St John's Church Failsworth this evening to celebrate with the local community in the arrival and induction of the new vicar to the parish.
"Officers returned to their vehicle to find the windscreen smashed.
"Enquiries are ongoing with local residents and CCTV to locate and bring the people responsible for this senseless act of criminal damage to justice.
"2 individuals in dark clothing were seen running towards Oldham Road at around 6.55pm.
"Anyone with any information please contact 101 to report."
