Three teenagers have been arrested after an attempted arson at Shilbottle First School.
At 1.20am on Saturday, May 11, a bottle filled with flammable liquid was thrown at a rear window.
The bottle failed to ignite but the offenders returned, lit it and threw it again, causing damage.
A 19-year-old man and two boys aged 13 and 14 have been bailed pending further inquiries into the incident, but police are still appealing for anyone with any information about it to get in touch.
Headteacher Angela Jefferies said: “I have been head here for 17 years and we have never had vandalism like this before.
“It has shocked the whole school community.
“Fortunately it was only one window that was damaged and it was double glazed so the fire didn’t go through.”
Alnwick Neighbourhood Inspector Paul Truscott said: “This was an extremely dangerous thing to do and won’t be tolerated. We have not had an incident like this in Shilbottle before and to reassure residents we have extra patrols in place and these will continue over the coming days.
“As part of the investigation officers have been carrying out house-to-house inquiries in the area and checking CCTV.”
Police have spoken to staff and teachers at the school and will be going in to speak to pupils about the dangers of fire.
Anyone with information should contact police on 101.