"We consider these five escapees to be the most dangerous and desperate people on the streets of Australia at the moment and police are absolutely petrified and terrified as to what they may do to remain at large," a police media spokesman, Brian Swift, told a news conference.
The prisoners, said by police to be armed, used diamond-encrusted wire to break out of Brisbane's maximum-security Sir David Longland jail in the early hours of yesterday.
Police used helicopters after possible sightings in Brisbane's central business district and had earlier warned people in the city's outer suburbs to lock their houses and cars.
Using diamond-encrusted "angel wire" smuggled into the jail, the prisoners cut through the bars of their cells, then used their bed sheets to winch open the bars, said prison officials.
The prisoners then used cell chairs to scale a fence crowned with two rolls of razor wire.
After cutting through three more security fences, the prisoners reached the jail's perimeter fence and were thrown bolt-cutters by two people outside the jail.
The accomplices, armed with a high-powered rifle, began shooting at a guard who was chasing the prisoners as the jail's alarm began to sound.
A volley of 10 to 12 shots was fired, several piercing an armour-plated prison van which was patrolling the jail.
"When the patrol vehicle got to within 70 metres [230 feet] of the perimeter it was fired upon and both of its batteries were destroyed," said the Corrective Services Commission spokesman, Stan Macionis.
One bullet pierced the unarmoured roof of the van but the two officers inside were not hit.
The prisoners and two accomplices then ran down a road to a waiting car and sped off. A police car gave chase, but pulled back when fired on.
The Queensland Police Minister, Russell Cooper, has ordered all prisoners to be locked in their cells pending a report on the massive security breach.
"This is the first time we have had a concerted external assault on a perimeter in such a ruthless and cold, calculated way," said Mr Macionis.
One of the prisoners, Brendan Abbott, is nicknamed the "Post Card Bandit" for sending police taunting holiday picture postcards of himself holding bags of money while on the run.
Abbott, 35, was serving a 12-year term for bank robberies. The other prisoners are Jason Nixon, 27, serving life for murder, Oliver Alincic, 32, serving life for murder, Andrew Jeffrey, 20, serving life for murder and Peter Sterling, 31, serving 13 years and seven months for deprivation of liberty.
Reuters - Brisbane