A number of Sydney schools have been evacuated and police are investigating reports of a threatening email. 

A police operation is underway, and HSC exams were paused.

There are no reports of anyone being injured.

Some of the schools believed to be affected include Castle Hill High, Thomas Reddall High in Ambarvale, Willoughby Girls High, Colo High and Jamison High.

The schools were evacuated as a precaution.

HSC Legal Studies student at Castle Hill Josh Gatt told Deborah Knight students had 50 minutes left on their exam when the alarm was raised.

“At first we were like ‘what’s going on?’ and one of the teachers was like, ‘oh, there’s been a bomb threat’.”

Click PLAY below to hear the full story

A spokesperson for the NSW Education Standards Authority said they were aware of reports a number of high schools activated their emergency response plans this morning.

“NESA is working with the school sectors to understand the impact on HSC exams,” the statement read.

“Impacted students will not continue exams unless it is safe to do so. No student will have to re-sit an exam.

“Schools will submit to NESA group applications for illness and misadventure on behalf of impacted students.”

NSW Police have launched an investigation into the origins of the emails, which were sent to at least 19 schools.

2GB senior reporter Clinton Maynard told Jim Wilson the schools have since been declared safe, and most of the afternoon’s exams have gone ahead as scheduled.

Click PLAY below to hear the latest update

Image: Nine News