Staff and pupils at St James' Primary School have been left heartbroken after vandals trashed their play area - the third time in a matter of months.
Thousands of pounds worth of damage has been caused after the offenders left a trail of destruction at the Greenacre Street school.
Drugs packets, cigarettes and rubbish were left, as well as a shed destroyed which was paid for by youngsters who sold toast every morning to raise the cash.
The school has been repeatedly targeted by trespassers in the past few months.
Now, police have vowed to punish the vandals responsible for the damage, but they are also urging parents to keep an eye on their children and to come forward with any information.
PCSO Natasha Harris, of Clitheroe Police, said: "About £1,000 worth of damage has been caused this time to the school. This sort of behaviour cannot go unpunished and I would urge the parents of teenagers in Clitheroe to PLEASE ask your child if they know anything about the damage that has been caused to the school grounds.
"This school is at the heart of our community and we are appalled at the damage that has been caused. St James' is a fantastic school and the facilities provided for the children to play with are brilliant, so it is very unfair that a small group of youths think it is ok to cause mindless damage with no consideration for how it might make the young children feel when they return to school in the next few weeks."
In a Facebook post, a school spokesman said: "Absolutely disgusted to find our school playground, worship area, gazebo and shed destroyed. Litter, cigarettes and drugs packets everywhere. Thousands of pounds worth of damage. Please, please share and if you have any information on who is trespassing on our grounds then please message or contact Police on 101."