A technical college in the Dutch city of Leiden -- where schools were closed and armed police deployed early this week after a threat of a mass shooting -- was evacuated on Friday because of a bomb alert, police said.
"The school (for further education) was evacuated after a bomb threat," police spokeswoman Welleke van Rantwijk told AFP, adding that there was "apparently no link to the threat" made earlier in the week.
"The school is now empty, the police are there investigating," she said.
Around 300 people were evacuated from the premises after the threat was made "a short time ago," Van Rantwijk said.
"I don't know how the threat was made," she said.
The college says on its website that it has around 7,000 students.
Authorities in Leiden had decided late Sunday to close secondary schools to thousands of pupils after a tip-off by Swiss police following the online threat.
"I will shoot my Dutch teacher and as many students as I can," said the anonymous message in English on the 4chan.org website.
"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.
City authorities lowered the threat level on Wednesday after tracing the Internet threat to Costa Rica.
Police said on Friday that an 18-year-old Dutch suspect living in Costa Rica was going to return voluntarily to the Netherlands, but could not say when.
A former pupil at the British School had initially been arrested over Sunday's threat.