Police have arrested a fourth suspect in connection with an ongoing dispute between teenage gangs that led to five schools being closed last Friday.

Secondary schools in Heemskerk and Beverwijk, around 20km north-west of Amsterdam, closed their doors, while lessons were cancelled at Nova College in Haarlem following a string of violent incidents.

Videos were posted online showing pupils being assaulted, including one in which a gun was placed in the victim’s mouth, while others contained AI-generated images of school buildings on fire.

A 19-year-old man from Beverwijk and an underage boy from Haarlem were arrested over the weekend on suspicion of possessing illegal weapons, while a 20-year-old from Heemskerk was arrested for alleged incitement.

The mayor of Beverwijk, Martijn Smit, called the situation “disturbing”. “Several criminal investigations are ongoing,” he said.

An emergency order has been issued authorising police to carry out preventive stop and searches in the area until October 9, aimed at curbing the ownership and use of illegal weapons.

Smit said he had taken the decision to close the schools after consulting administrators and the police, but stressed that children were not in danger as the schools opened as normal on Monday morning.

“It’s always been safe,” he said. “The unrest was mainly spread online and between a few rival groups. We will act strongly to anyone who uses violence or spreads fake news.”