Dutch police arrested a former pupil at a British school in the Netherlands on Monday in connection with a threat to go on a shooting spree that saw armed police deployed and schools closed.
Police in the university city of Leiden, just northeast of The Hague, confirmed one person had been arrested following the threat to "shoot my Dutch teacher and as many students as I can", made on an Internet site over the weekend.
"Someone was arrested in connection with the threat and we're continuing our investigations," a police spokeswoman said, declining to give her name.
"We have been informed that a former student of the British School in the Netherlands (BSN) has been arrested in connection to threats made against a Dutch school in Leiden," said a statement issued by the school.
The British School in Voorschoten, between Leiden and The Hague, said the pupil was expelled in October 2011 "after incidents regarding his behaviour and has therefore not attended the school for over a year."
Police informed the school that there was never a threat to the British School or to its students, the school said, adding that it had remained open on Monday.
Founded in 1931, the expensive private school hosts students of 80 different nationalities, according to its website.
Authorities in Leiden decided late Sunday night to close secondary schools to thousands of pupils following a tip-off by Swiss police following the threat.
"I will shoot my Dutch teacher and as many students as I can," said the anonymous message in English on the US-based online forum 4chan.org.
"It's at a school in the Dutch city of Leiden" it said, chillingly adding "for more proof, I will be using a 9mm Colt Defender."
"Oh, and I'm using a proxy, the police is not gonna find me before tomorrow," the message ended.
In a statement late Sunday, law officials said they did not yet know against which school the threat had been made and warned parents not to send their children to class.
An AFP correspondent said that besides the cordoned-off schools and the police presence, life in the city appeared to be continuing normally.
Leiden mayor Henri Lenferink told the NOS broadcaster "we received a report via the police in Zurich, who saw the posting on the Internet and gave it through to the police in Leiden."
"They tried to establish who placed the text but that was not immediately successful. There has also been and still is, contact with the FBI in the United States" to see if the person can be traced, Lenferink said.
He said after running out of time, the decision was taken to close the schools because "if you can't find the perpetrator or know exactly which school is being targeted, only that it's a school in Leiden... you have to do something."
Lenferink added that "of course its possible that it's a morbid joke."
"On the one hand you don't want to overreact, on the other nobody wants to take the risk -- that's the difficult dilemma we were facing yesterday," he said.
Secondary schools in the Netherlands cover the 12-to-18 age group and there are at least 22 such schools in Leiden -- some of them international. The city is home to the country's oldest university.
Dutch police in 2009 arrested an 18-year-old man for posting threats on 4chan.org.
The man, who threatened a shooting at a school in the southern city of Breda, later said he did it as a joke.
The 4chan.org website describes itself as a "simple image-based bulletin board," covering a variety of topics including video games, sports, Japanese anime and pornography.
In April 2011, a man armed with a semi-automatic rifle killed six people when he opened fire on shoppers at a mall in the western town of Alphen aan de Rijn.
Gunman Tristan van der Vlis, 24, then committed suicide, in what was the worst mass shooting in recent times in the Netherlands.
In 1999, four students and a teacher were wounded when a student fired 10 shots in a computer room at a school in the southern Dutch town of Veghel.