A police operation is underway at several schools across Sydney after threatening emails were reportedly sent to them. 

The schools that have reportedly been affected include Willoughby Girls High School, Thomas Reddall High School, Castle Hill High School, Jamison High School, Colo High School and others that are yet to be confirmed.

Police have told us that the same threatening email was sent to several schools across Sydney, prompting all students and staff to be evacuated from all locations.

An HSC Legal Studies exam was underway, and was likely disrupted.