Seven teenagers remain on the run after escaping from the Malmsbury youth detention centre on Wednesday amid a riot where a guard was attacked and had his security pass stolen.
About 30 inmates rioted at the centre on Wednesday afternoon, where a number of youths assaulted a staff member and gained access to his keys.
Some of the escapees allegedly rammed a car on the Calder Freeway, terrifying a couple and their young grandchild.
Ray Blackmore told 9NEWS several youths carrying iron bars leapt from a vehicle which rammed his car on Wednesday afternoon.
"This other vehicle came across the median strip and came straight towards us," Mr Blackmore said.
"We realised once they jumped out of the ute with iron bars that we were in trouble," he said.
One of the youths shook the car door where Mr Blackmore's wife, Judy, was sitting,
She believed the group stopped when they realised their young grandchild, Ally, was also a passenger in the car.
"As soon as they spotted her, they backed off," she told Channel Nine.
Fifteen detainees initially escaped from the facility, stealing cars, ramming other vehicles and prompting police pursuits.
The escapees led police on two high-speed pursuits of up to 160km/h, before police were called off.
Six of the escapees were arrested after a pursuit in the Bendigo area which finished at Lockwood, where a police vehicle and a stolen vehicle were involved in a collision.
Two others who escaped the Malmsbury facility on foot were found walking shirtless through paddocks about five kilometres from the detention centre.
Four of the teenagers were involved in an alleged hit and run in Mulgrave overnight.
A white Suzuki SUV, which several escapees had been travelling in, was involved in a collision with another vehicle and dumped at the intersection of Springvale and Wellington roads about 11.40pm.
Police said the occupants fled the scene but did not know if they had secured another vehicle.
The SUV had earlier been been spotted in Fountain Gate, in Melbourne's outer south-east, while another vehicle carrying three escapees, a blue Ford XR6 sedan with registration ZKV 598, had been seen in Werribee, on the city's western fringe.
"A large number of police including specialist units from operations response unit, public order response team, dog squad, fugitive taskforce and critical incident response team are all working to bring this incident to a resolution," the statement said.
Victoria Police Assistant Commissioner Rick Nugent said the escapees were 16 and 17-year-olds and police were still looking into releasing their identities and names.
He said police did not know where the escapees were headed, but police were pursuing every lead, including family and friends.
Mr Nugent urged the seven on the run to hand themselves in at a local police station, and warned the public that they were dangerous.
"It is just a matter of time before they are arrested, it is just a matter of time before they are put back in the facility."
Members of the community are asked to call triple zero if they see either of the vehicles and not to approach them. Those arrested are yet to be charged.
- Do you know more? Did you see the car chase? Email scoop@theage.com.au.
Police were initially called to a disturbance involving around 30 inmates about 2.45pm.
Police dressed in full riot gear and members of the youth justice safety emergency response team worked to regain control of the facility.
The riot was described by a source as "the worst they had ever experienced" at the problem-plagued correction centre.
"Clients were bashing at the door with chair legs and other weapons, then used the swipe to open the door," the source said.
The source said the youths stole keys and a swipe card from a guard, before a "code white" (a riot) was called.
Police confirmed the riot started after a number of youths assaulted a staff member and gained access to his keys. The staff member received minor injuries in the incident, police said.
Police said there was minor damage to the inside of the facility, including smashed windows and a small fire being lit.
One inmate suffered a minor injury while being arrested, police said.
Staff were released at 7pm, after four hours in lockdown.
At 8pm, police released a statement saying they had secured the facility.
A police car was rammed during the escape, according to media reports.
The 15 youths initially escaped by stealing a ute and ramming a fence at the detention centre.
The escapees dumped the ute, before stealing three other vehicles and reportedly smashing into another car on the Calder Freeway.
Police reportedly abandoned one high-speed pursuit after an allegedly stolen car started driving on the wrong side of the road on the Calder.
Earlier, Superintendent Craig Gillard confirmed that 15 inmates were involved in the breakout.
"There were five youths climbing on the roof of the facility and an additional 15 youths have breached the outside parameter of the facility," he said.
"We had a number of incidents external to this facility, around theft of motor vehicles. They have had three motor vehicles involved in use by these youths, we believe. One vehicle came from carjacking on a highway, another vehicle has been involved in a petrol drive-off," he said.
"The incident is still live ... it is still incredibly fluid. We still don't have security here to the level we would like."
Teenagers from the Monash and Latrobe units were involved.
The latest events come less than two weeks since police were forced to storm the centre after six inmates armed themselves in a secure unit. Four of those offenders have since been moved into the adult prison system.
On Wednesday, Fairfax Media revealed that the Andrews government was warned in an explosive secret report months before the latest riots in Victoria's youth prisons that the system was spiralling out of control in "a continued and ongoing threat to the safety of staff and clients".
Fairfax Media can also reveal that the man who ran the Parkville and Malmsbury youth justice facilities, Ian Lanyon, has recently been moved from his post, leaving an acting director in his place.
Fairfax was unable to reach him for comment.
On Wednesday, Opposition Leader Matthew Guy said Victoria's youth justice system was in crisis.
"These people are causing crime wave after crime wave," he said.
Mr Guy said Youth Affairs Minister Jenny Mikakos should resign if she could not fix the system.
Mr Guy said juvenile justice should be moved from the Department of Health and Human Services to the corrections portfolio.
with Marika Dobbin-Thomas and AAP