The detainees were also banging on the windows of a prison van as it drove out of the Youth Justice Centre on Monday afternoon.

The move comes after the Andrews government revealed that offending inmates would be transferred to adult prison.

"Enough is enough, these perpetrators of this damage will face serious consequences," the Minister for Children, Jenny Mikakos, said.

She also announced that the government was considering new laws to punish the "disgraceful" behaviour that has plagued Victoria's youth justice centres recently.

The government has begun the legal process – Ms Mikakos did not elaborate on what that was – to transfer "a number" of offenders from Parkville to adult prison.

The minister made the announcement as heavily armed members from the special operations group entered the Parkville facility on Monday afternoon.

A source at the centre says ladders had also been set up around the unit, which could indicate that SOG officers were preparing to storm the building.

In the past few hours, a Domino's Pizza driver also delivered four large pizzas to the facility.

The Department of Health and Human Services later said "no prisoners got any pizza".

The dog squad was also at the scene.

The government said the riots had damaged the "operational capacity" of the centre but there were no injuries to staff or inmates.

Ms Mikakos also said that a plan to redevelop the Parkville site would be expedited but would not put a price tag on the project.

She said it had become apparent that the infrastructure at Parkville was "letting us down".

She also revealed that 80 per cent of the inmates at Parkville were on remand.

Police were called to a "code white" at the troubled Parkville centre about 9pm on Sunday night.

It is believed a number of fires were lit and fire crews and paramedics are on standby.

The disturbance follows a tumultuous weekend at the centre which caused an estimated $2 million in damages after inmates ripped ceilings and walls apart on Saturday night.

Sources told Fairfax Media that some of the inmates involved in Saturday's rioting had been moved to Malmsbury Youth Justice centre and to other units within Parkville.

About 20 inmates at the facility were left without beds on Saturday after their cells were trashed.

It is believed inmates destroyed security cameras and ripped ceilings and walls apart.

Saturday night's riot came as an inmate at another prison facility attacked four prison officers, inflicting a serious neck injury.

Streets in Parkville were blocked as police dealt with the riot at the Youth Justice Centre.

Inmates at the juvenile facility destroyed security cameras, computers, and ripped the ceiling and walls apart during the riot, a prison source said.

It's believed the sprinkler system was also severely damaged after the group broke into one of the buildings and found a sledgehammer and shovel.

Computers were then thrown through the windows before the group climbed up on the roof and demanded junk food and a phone, the source said.

No youth justice officers or inmates were injured during the incident.

The riot only ended after police called in the dog squad.

The disturbance is believed to have been started by the same youth who triggered another riot on Thursday at the centre.

Community and Public Sector Union spokesman Julian Kennelly said officers had contacted the union about the riot, saying about 20 teenage inmates were involved and that the trouble centred on three residential units.

'They're packed in like sardines'

Former commissioner for children Bernie Geary said the problem was that the majority of the children at Parkville were languishing on remand, "packed in like sardines", before they were found guilty of an offence.

"The more they treat these young people like adult prisoners the more likely they are to act like adult prisoners," he said. "The system is failing to deal with kids in the justice system."

He said for many children a stint on remand encouraged a cycle of re-offending. "There are all these kids there who are angry, anxious, scared. And they don't know what is going to happen to their lives, there are no plans, they have no ambition. They have just been herded in there, waiting for the system to catch up with them."

Mr Geary called on the government to amend the Bail Act to exempt children to ensure children do not spend months on remand while awaiting sentencing.

Minister for Families and Children Jenny Mikakos said since rioting began, a number of inmates had been detained and that all were contained within the facility.

"There is no threat to the security of the facility being breached. There are no hostages. There are no fires. There have been no staff injuries," she said in a statement.

"I want to thank Victoria Police and the youth justice staff for the work that they're doing," she said.

"This behaviour is completely unacceptable and staff shouldn't have to put up with it.

"We are developing a range of tougher measures to ensure we put a stop to this."

She hinted that she would reveal more information about the "tougher measures" on Monday afternoon.

Earlier this month, Ms Mikakos announced that any youth inmate who assaulted a staff member or was involved in any other serious incident would have the matter reported to the parole board.

"We are developing a range of tougher measures to ensure we put a stop to this," she said on Sunday.

State government minister Richard Wynne condemned the rioting.

"The government is obviously really concerned about the events that occurred at the Youth Justice Centre ... and, in fact, we have just put on 41 staff to ensure that the centre remains secure," Mr Wynne said.

Ambulance Victoria spokesman John Mullen said paramedics were initially called to the centre due to reports of youths on a roof and were on standby but were not required.

Department of Health and Human Services spokesman Mike Griffin said the department would "thoroughly examine" the circumstances leading up to the incident.

"The behaviour of these clients on Saturday was unacceptable and staff shouldn't have to tolerate it," he said.

Changes in policy could see the riot reported to the Youth Parole Board and may affect the parole eligibility of those involved.

Troubled times

The centre has been plagued by violence in recent times.

In September, inmates and staff clashed for three consecutive nights and several juvenile offenders threatened staff and took control of part of the centre.

Amelia Banks, who lives nearby, said she heard a "police helicopter and a stream of emergency vehicles driving past with sirens blaring".

She raised concerns that the rioting was becoming frequent and worried about the safety of the children and officers inside.

"Whatever happens inside the centre clearly isn't working as the children who are in custody seem to be ready to riot at any given moment," Ms Banks said.

Alana Marzuke, who also lives nearby, said she saw up to seven police cars at the scene.

In the separate prison incident on Saturday night, four Port Phillip Prison officers were assaulted during a cell search, with one suffering a suspected serious neck injury.

The prison officers were searching an inmate's cell after visiting hours to check whether he had received contraband.

Paramedics were called to the Truganina prison at 7.10pm and transported the officer, aged in his 30s, to hospital. Ambulance Victoria confirmed the man was in a stable condition.

Mr Kennelly said the inmate was believed to be using drugs.

"If he has taken down four officers, we would suspect it was ice or something similar," he said.

The prison was placed in lock-down, Mr Kennelly said.

Three other prison officers were treated for minor injuries, and capsicum spray was used to subdue the prisoner.

He said Port Phillip Prison's contraband detection system was inferior to other prisons around the state and called for the private operator, G4S Australia, to upgrade it.

Mr Kennelly said contraband was rife in Port Phillip Prison, and this, added to overcrowding, was making it difficult and sometimes dangerous for prison officers.

"Port Phillip was built 20 years ago to house 600 inmates and it is now housing nearly double that," Mr Kennelly said.

Opposition corrections spokesman Edward O'Donohue said the justice system was in crisis.

"Further evidence overnight that the justice system in Victoria is in crisis with young offenders rioting at the youth justice centre, while prisoners at Port Phillip are attacking staff and reportedly taking ice," Mr O'Donohue said.

Prison operator G4S said it used "robust and proactive" security measures, which were having a positive impact on safety at the facility on a daily basis.

"We employ multiple strategies that are incorporated with modern systems to stop the flow and demand of contraband," G4S director Brett McMerrin said.

"G4S is dedicated to managing the safety and security of staff, prisoners and visitors."

With Deborah Gough, Goya Dmytryshchak, Steve Lillebuen