5.15pm: Primary schools in Hamilton and Portland were evacuated today after receiving what were believed to be hoax bomb threats.
The threats coincided with similar phone calls made to schools across Australia and New Zealand.
Across Victoria, schools enacted their emergency management plans and students were moved from buildings as a precautionary measure, Victoria Police said.
Police would not confirm how many schools were affected, or the specific nature of the threats, but said the schools involved were not limited to one area.
Police in various states said the incident appeared to be similar to a spate of hoax calls that sparked evacuations and lockdowns at dozens of schools across Australia earlier this year.
At least six schools in Victoria were evacuated.
One school principal told Fairfax Media the call carried an automated message saying there could be an explosive device in the school and students could be hurt.
Meanwhile, police in Queensland, Tasmania, NSW and the ACT responded to incidents at schools across those states.
Police in both Queensland and Tasmania said they suspected the threatening calls were similar in nature to those that had occurred in February, when automated calls were made to schools Australia-wide and later revealed to be a hoax.
"We are liaising with the Education Department and remind people that making threatening phone calls is a serious criminal offence," a Queensland Police spokesman said. "These incidents will be investigated fully."
In Tasmania, calls of bomb threats were made to three schools around 10am, within the space of five minutes, police said.
After attending the schools and conducting enquiries, Tasmania Police said in a statement that: "no concerns were identified and classes resumed".
In New South Wales, police said operations were under way at schools across the state, but did not specify whether they were in response to threatening calls. However, it is understood the incidents were of similar nature to those in other states.
Two schools in the ACT received threatening calls, but after being cleared by ACT Policing, students were sent back to class.
West Australian police had not, as of late morning local time, recorded any incidents of threatening calls to schools in the state.
The threats made across Australia coincided with threats to schools throughout New Zealand.
New Zealand Police said in a statement on Thursday morning that they were "responding to calls of a concerning nature directed to a number of schools throughout the country".
"We understand the fear and concern that these calls cause, however we reiterate that so far we have not established any actual threat to any school."
New Zealand Police added that Thursday's calls "may be similar to those received earlier this year, which inquiries indicated originated overseas".
In February, a spate of hoax calls sparked evacuations and lockdowns at dozens of schools across Australia, including almost 20 in Victoria.
At the time, police were investigating whether a hoaxer had hacked into the telecommunication service at select-entry state school Nossal High School, located at Monash University's Berwick campus.
A Russian hacking gang called Evacuation Squad claimed to be responsible for the dozens of threats in Australia, as well as similar ones made in the UK, Hawaii, Paris, Japan, the US and Guam over the course of a few weeks.
It is understood some of the phone calls featured an electronic voice message, however it was not clear whether all schools received an electronic message.
At the time, a spokesman for the group calling himself Viktor Olyavich told Fairfax Media via email that the hackers would carry out more bomb threats in the future.
It is not known whether the Russian group is responsible for the latest round of threats.
1.30PM: George Street Primary School has resumed classes after students were evacuated for two hours.
Sergeant Mark Phillips, of Hamilton police, said the school had been cleared by police.
A school in Portland was also believed to have been locked down, but it is unclear whether classes have resumed.
The schools enacted their emergency management plans after receiving a threatening phone call.
11.26am: Official statement from Victoria Police media department:
“Victoria Police is aware that a number of schools across the state have received a threatening phone call today.
“Those schools have enacted their emergency management plans as a precaution.”
Anyone with information is urged to contact Crime Stoppers on 1800 333 000 or go to www.crimestoppers.com.au and submit a confidential crime report.
11.25am: HAMILTON police have confirmed George Street Primary School has been evacuated as a precaution.
All students are accounted for, a police officer said.
Hamilton police said no other schools in the Hamilton area were in lockdown.
11.10am: SCHOOLS in Portland and Hamilton have been placed in lockdown following a series of threatening phone calls.
Police confirmed the schools, along with others across the state, were shut down as a precaution.
3AW reported lockdowns at Portland, Hamilton, Traralgon, Ballarat, Bendigo and in the state’s north east.
Anybody with information is urged to contact Crime Stoppers on 1800 333 000.