Why parents aren't laughing about April Fool's Day joke

EDUCATION officials don't see the funny side of an April Fools' Day prank which saw an emergency SMS message sent out to 1000 parents saying a school had been damaged by fire and closed for the day.

The New South Wales Department of Education confirmed the Castle Hill High School's computer system appears to have been hacked, the ABC reported.

The school was forced to issue a statement on its website saying classes were on.

Please disregard text message sent earlier this morning.

There is no malicious damage to the school.

School is open today as normal and Year 12 Half Yearly Exams will go ahead as per timetable.

Education Minister Adrian Piccoli is promising swift retribution if the person responsible is found.

"I mean April Fools, if they are harmless jokes are fine, but something like that, a huge disruption and a huge amount of anxiety for hundreds of parents is not a joke," he said.

"I just think it is a stupid thing to do.''