Bomb detection dogs were brought in to search the school while students assembled in the back oval.  

Lake Illawarra Police's Sergeant Jason Harrison would not comment on the specifics of the threat, but said it differed from a spate of threats made in Australia and overseas using a telephone system. 

“An email was utilised on this occasion. [The threat] didn’t look like it was of the same kind of nature,” he said. 

An investigation into source of the threat is ongoing.