A wave of violence and vandalism at schools around the country, with one young man wielding a gun in an incident in Crete, has put teachers and police on alert.
The unrest has broken out as the number of sit-ins at schools dwindled on Monday to 271, from 450 last Friday, according to authorities. The pupils, who are protesting spending cutbacks, put the number of sit-ins much higher at 813.
Most of the incidents were reported at schools where sit-ins have ended.
In a secondary school in Zografou, eastern Athens, teachers found the classrooms vandalized and computers and desks stolen.
The Evangelical School in Nea Smyrni was one of several institutions targeted by arsonists.
At a school in the village of Arkalohori, in the Cretan prefecture of Irakleio, a group of youths tried to join a sit-in but were pushed back by pupils, prompting one of the intruders to pull out a gun. The pupils managed to defuse the situation before police intervened, detaining the assailants and their parents.