Thugs targeted an infant school, smashing ten windows and scrawling graffiti across the roof.
The windows were smashed in Trafalgar School, Victory Road, Horsham, overnight on Thursday to Friday, Sussex Police confirmed.
A statement said: "Nearby resident heard loud noises around midnight."
The school added: "Some windows were broken at Trafalgar Community Infant School.
"Graffiti was also sprayed on the premises. The school community was very saddened by this but worked together to get the school ready to be open as usual. The children are all safe and repairs are underway.
"Thank you to our school and local community for their support and if you have any information related to this incident then please contact the school or the police on their non-emergency number 101."