Police operations are underway at several schools in Sydney as a precaution following “numerous threats,” the New South Wales Police announced Monday. According to reports, two schools have been put in lockdown.

“Police are warning that making threats is a serious criminal offence and every effort will be made to identify the person or persons responsible,” the NSW Police said in a statement.

Sydney Girls High School was reportedly evacuated, with witnesses saying a large police presence was seen at the school. According to local reports, the police operations have closed Cleveland Street and South Dowling Street in Moore Park. Sydney's Girls High School is on Cleveland Street in Surry Hills.

The Department of Education also confirmed Monday that police were visiting each school as a precaution.

"Each school is taking precautionary measures to ensure the safety of its students and no students are in danger," the department said, in a statement, according to ABC News. "Concerned parents can contact their child's school."

Last week, at least 15 schools in NSW and Victoria were evacuated after receiving threatening phone calls. Police reportedly searched several schools at the time before determining that the calls were a hoax.