Stuff like this has happened in the past in the USA. In the Netherlands this hasn't happened yet, fortunately.
Do you think it was just a joke? Looking at the situation, I think the threat wasn't real. Nonetheless, it is still good that the police was actively taking precautions to prevent a shooting. But then again, if this has to be done for every (serious?) threat on 4chan... What do you think?
Image: http://i.imgur.com/vsKDjoZ.jpg
Source: http://www.nu.nl/binnenland/3403692/verdachte-opgepakt-bedreigingen-leiden.html
Suspect arrested for threats Leiden
Police have arrested a suspect in connection with the threats about a shooting in Leiden.This was confirmed by the Haaglanden police on Monday. The possible shooter is a former pupil of The British School in The Hague.
The Telegraph also reported that a firearm was found at a school in Leiderdorp. A police spokesman responded to that message. It turned out to be a toy gun.
The police received a report Sunday about a possible shooting in Leiden. By order of the police and the municipality it was decided to keep the schools closed on Monday.
An unknown person on the internet posted a threatening message which talks about a possible shooting that will take place within days. "Given the seriousness of the threat it was decided to take no chances," said the police report.