And some schools have introduced "active shooter" drills, where children are taught to hide in class to avoid being seen by armed offenders. Police have briefed Education Department officials on "lock down" and evacuation tactics to combat intruders.

The policy shift means junior police who are first at the scene need to be trained to confront and possibly kill armed terrorist and mass shooters. They are also being taught to try and "lock in" suspects in a contained space to minimise casualties.

Under the new rules the first police at a scene will be prepared to immediately engage armed offenders who refuse to surrender rather than wait for specialist back-up. The policy, known as "casualty reduction", will be used when police reasonably believe hostages are likely to be murdered.

Assistant Commissioner Kevin Casey said while police will always try to negotiate a peaceful outcome they also need to prepare for offenders, including home grown terrorists, intent on causing multiple casualties. "We are living in a different world now," he said.

As part of "Active Armed Offender" training police are using a $1.8 million computer virtual reality scenario program that can replicate more than 100 potentially violent confrontations.

The training will soon include options to deal with offenders who use vehicles to plough into crowds - such as Melbourne's Bourke Street killings that resulted in seven deaths and the 2016 Nice attack that cost 86 lives.

The shift in policy follows a review of Sydney's 2014 Sydney's Lindt Cafe siege that found traditional police tactics are ineffective when dealing with modern terror plots.

Since 1994 police have been trained under Project Beacon - where the safety of police, the public and suspects is the highest priority. The centre point of the tactic is to contain the threat and wait for specialist police to take control.

The proven policy was based on the view that the longer a siege lasted the more likely it would resolve peacefully.

But local and international terror events have shown terrorists may pretend to negotiate in order to maximise publicity but intend to kill as many hostages and police as possible before dying in the final shoot-out.

After the Lindt Cafe siege ??? where police stormed the building after a hostage was killed ??? police have moved to a new model of early intervention where direct action that includes an element of surprise is preferred to emergency action where police move after shots are fired.

Superintendent Peter Seiz said terrorist attacks and high school shootings across the globe have driven the change.

"Our oath of office is to protect life. The community expects us to be that line in the sand and to take action if needed to keep them safe," he said.

About 13,000 police have received the first phase of the training and will now be taught a more sophisticated version to be kept up to date with terror trends.

The scenario training includes dealing with drug-affected suspects, armed mentally ill offenders, potentially violent domestic incidents as well as full-on shooting emergencies.

In one drill police have to run into a school mass shooting to locate several gunmen.

"It's the reality of the world today and we need to prepare ourselves," Superintendent Seiz said "Our job is to protect life first and foremost and we might need to get into or resolve a situation where a decision might have to be taken to take an offender's life."

Police will still be able to use cordon and manage tactics where there is no immediate threat to life.

Senior police are also considering equipping the elite Special Operations Group with motor bikes to arrive quickly at siege scenes and take action before their full equipment arrives in support vehicles.