Former pupil arrested over mass shooting threat at Dutch school

A former pupil of one of the Netherlands's best-known colleges for the children of expatriates was under arrest last night after an online threat to carry out a mass shooting at an unnamed school in the university city of Leiden.

The warning was posted anonymously in English at the weekend on the image-board website, 4chan.org – a favourite with teenage sub-cultures – and read: “Tomorrow, I will shoot my Dutch teacher and as many other students as possible”.

It is unclear whether the author was male or female, but the post also said they would use a 9mm Colt Defender pistol to carry out the shootings and would carry a note to explain their motives later. A picture of the gun was included in the post.

The threat was first discovered by Swiss police and when Dutch detectives failed to identify the source by Sunday, the Leiden authorities decided the city’s second-level schools would have to remain closed yesterday – with thousands of students forced to stay at home.

Privately, police sources acknowledged that the decision to close the schools would send the wrong message to anyone else thinking of issuing threats – but said they had no option but to take every precautionary measure.

“Every idiot who sticks a threat on the internet can paralyse half of society,” said Ton Duif, chairman of the head teachers’ association, AVS.

One parent, Frans van der Mark, said he received a call late on Sunday night advising him to keep his children at home.

“I have to admit I was trembling when I put the phone down,” he said. “I couldn’t sleep as a result. You always worry about your children.”

Last night police confirmed they had arrested a former pupil of the British School in the Netherlands in Voorschoten, near Leiden, in connection with the threat.

This was also confirmed by the school, which was open but had additional security yesterday.

It’s understood the pupil was expelled in October 2011 for inappropriate behavior and has not been seen at the school since.