Facebook group 'Facebeef' has claimed to be behind Castle Hill High School April Fool's Day prank.
On Tuesday morning students and their parents woke up to a hoax text message claiming there had been a fire at the school and it had closed.
They were quickly informed by the school it was an April Fools Day prank.
At 11.37am, parents and students received a second text message.
It said: ‘‘Hey there - As you may already know, the previous messages were sent as part if an April Fools Prank and school did go on as usual. I understand how this may have inconvenienced some people, but you really should have looked at your calendar before believing.’’
Last night one of the members behind the internet activist group Facebeef claimed to be behind the hoax.
Facebeef became famous for duping Today Tonight into a fake trolling story.
A Department of Education spokesman said the school's text messaging system was shut down and the school will not going to use the system until it's okay.
The matter was referred to the police.
Hills crime manager Detective Inspector Gary Bailey said it could be an offence under the Commonwealth Crimes Act.
A Castle Hill police spokesman said while numerous people had claimed responsibility for the prank no one had come forward so far.
He said they started receiving calls some time in the afternoon.
‘‘We’ve had a number of leads,’’ he said.
‘‘We’re responding and investigating.’’