An April Fools' Day prankster who duped parents into believing Castle Hill High School had burnt down claims he or she should be given credit for "pulling off something this huge".
Parents receive school closure April Fools SMS
The Education Department is investigating a prank at Sydney's Castle Hill High School, after parents were told part of the school had burnt down.
The anonymous person, who breached the school's IT system, sent further emergency text messages and emails to parents on Tuesday, telling them: "You really should have looked at your calendar before believing."
The NSW Department of Education and Communities had already alerted police after discovering that an unknown person had "inappropriately accessed" the school's IT system and sent inaccurate text messages to the families of about 1100 students about 3am on Tuesday.
The messages incorrectly claimed that the school had been severely damaged by fire and that it was unsafe for students to attend on Tuesday.
Once the school identified the breach on Tuesday morning, staff alerted students and parents that it was a prank and that the school was open as usual. Police also were called in to investigate.
But that did not stop the prankster, who struck again about 11.30am on Tuesday.
The person sent two more messages to families who had provided their contact details to the school so they could receive emergency alerts.
"You really should have looked at your calendar before believing ... give me credit, it's not easy pulling off something this huge," one of the messages said.
The person used the same sign off as Anonymous, the online activist group.
Castle Hill High School has now cut off its text messaging system until further notice, deputy principals Anna Girginis and Ross Warren said in a statement sent to families.
"The Department of Education and Communities in association with the NSW Police will continue the investigation of this matter," the statement said.
"In regards to future methods of communication with parents we will now use email and the Castle Hill High School website as the only electronic forms of communication. We are very conscious of trying to maintain the privacy of personal details and as we move forward with the investigation we will provide you with further information as it comes to hand."
Earlier, a department spokesman said the original message sent to parents was "completely incorrect".
There are 1400 students enrolled at the school, and 1100 families received the messages.
"As soon as we became aware, the correct information that the school was open was sent to those who had received the initial SMS or email, and the school's website has been changed to reflect the information, as has the school's notice board out on the street," the spokesman said.
"The school, along with the department, will be investigating how this occurred. It will be reported to the police because there is a question of data security there.
"It may have only been an April Fools' Day prank, but we want to make sure that data is secure, that no other data has been accessed and obviously work to strengthen the system so it doesn't occur again."
The spokesman said the message would have caused distress to some students who were due to sit exams at the school on Tuesday, while some parents would have scrambled to try to organise last-minute supervision for their children.
"Disadvantaging and distressing parents and students is something we obviously don't want," the spokesman said.
"We will be working with the police on this and obviously if we find out who is responsible and it is a member of the school community, we will be taking disciplinary action against them. Obviously if the police find criminal activity involved, they will take the action that is appropriate."