POLICE are appealing for witnesses after two windows were smashed at Brae High School some time between Friday afternoon and Sunday.
Police said bricks were thrown through the windows at the rear of the building.
Constable Daniel Drummond said police were aware of what they described as “an ongoing issue”.
In April this year, the school was targeted by vandals when plastic piping was damaged and air vents were removed.
A spokesman said: “Police are aware that this is an ongoing issue and are appealing for anyone with information on this incident or similar incidents to get in touch.
“Similarly local residents are asked to report any suspicious activity around the school to police.”
Anyone with information is asked to contact police by phoning 101 or calling along Lerwick police station.
Police can also be tipped off anonymously via Crimestopper on 0800 555111 or online athttp://www.crimestoppers-uk.org/