North Yorkshire Police say they are treating the damage caused at Selby High School seriously and appealing to parents and guardians of children to check where they are at night, and if they returned home with paint on their clothing just after midnight today.
Officers believe four suspects trespassed onto the school grounds between 12.15am and 12.25am on March 9.
They then broke into the textiles room by forcing a fire door and causing considering damage within the room by throwing paint all over it.
The suspects are believed to have accessed and left the school grounds from Fairfax Avenue. Police have located a bike left on Fairfax Avenue which they believe could have been used by one of the offenders.
A force spokesman said: "We are requesting the public’s assistance to help establish the full circumstances surrounding the incident.
"In particular, we are appealing to local residents:
"Did you see or hear anything around the time of the burglary? Did you see anyone leaving the scene?
"Do you have any CCTV, dash-cam or doorbell camera footage that may have captured something?
"We are also appealing to parents/guardians and family members, did your child go out during the night? Did they have paint on their clothing when they returned?
"This matter is being treated seriously, after months of most children being forced to stay away from school, what should be treated as a happy return has now been ruined for some children thanks to the selfish and inexplicable actions of those involved."
Anyone with information is urged to call police on 101 quoting reference 12210074032.