A man is expected to be charged shortly with the stabbing death of 17-year-old Masa Vukotic in a park in Melbourne after he handed himself in to police.

He is set to face an out-of-sessions court hearing, which will be closed to the media due to "serious safety and security concerns", police said.

The Canterbury Girls Secondary College student's body was found near a footbridge in Koonung Creek Linear Reserve in Stanton Street, Doncaster on Tuesday night.

Neighbours called triple-0 after they heard screaming and saw a man fleeing the scene, but paramedics were unable to revive the girl who had been stabbed in the upper body.

Police have refused to confirm if the man was the same person who committed a violent crime spree in Sunshine this morning involving two assaults, a robbery and an attempted carjacking.

The man first allegedly assaulted a 26-year-old man on a footbridge at 10:00am before stealing his mobile phone. The victim was taken to the Sunshine Hospital.

The alleged assailant then attempted unsuccessfully to carjack a vehicle belonging to a 77-year-old man on McCracken Street.

The man then fled on foot before going into a business on Harvester Road about 11.20am when he approached a woman and allegedly became violent before physically and sexually assaulting her.

She was also taken to hospital.

Police said the man was arrested and was being interviewed.

Public assistance 'fantastic'

Police late yesterday released CCTV footage of a man running along Heyington Avenue minutes after the attack on Ms Vukotic and images of the same man after he boarded a bus on Doncaster Road.

Detective Inspector Mick Hughes said the man in the CCTV images handed himself in after a public campaign.

Man arrested over the fatal stabbing of teenage girl Masa Vukotic in a park in Doncaster, Melbourne, on Tuesday. ( Victoria Police )

He thanked the public for their "fantastic" assistance with the case.

"We've had massive support both in social media and I think we generated 100 information reports overnight," he said.

"We've got investigators in Doncaster, in the Abbottsford area where he was seen to get off the bus.

"We've had support services actively looking for a person of interest and this is the result of hard work."

He said police were not in a position at this stage to release the suspect's name, but that he was assisting with the investigation.

Man's connection with Doncaster unclear

Detective Inspector Hughes said the man, from Albion, in Melbourne's western suburbs, was known to police but not known to the victim.

"We have to keep in mind, he's a suspect in custody," he said.

"He's been cautioned and we have to be mindful of his rights. If ... he's charged, we'll release his name and all that information will come out from there."

He said it was too early to know if the suspect had a connection with the area of the attack.

"I said yesterday I believe the offender will know this area [but] we're still putting that together," he said.

"It is unusual... I used the word 'enclave' - it's a little bit of a sealed area, it's almost got roundabout roads.

"It smacked to me of someone that knew the location and as we put things together we'll probably find out there's a connection to that location."

School, community remembers Masa Vukotic

A small vigil was held at the park on Wednesday night and the local community and Ms Vukotic's friends left flowers at the site.

Flowers left for Masa Vukotic, who was killed in an apparent random attack at a park in Doncaster. ( ABC News: Gloria Kalache )

Police said Ms Vukotic's family, who moved to Australia from Montenegro, asked for privacy.

The principal of Canterbury Girls Secondary College, where Ms Vukotic was studying VCE, Dr Mary Cannon, said the school was shocked and devastated by the tragedy.

"Masa was a very popular and respected student who had close friendships with many students," Dr Cannon said in a statement.

"Our thoughts and wishes are with Masa's family at this incredibly difficult time."

Dr Cannon said additional specialist counselling for students and staff had been in place at the school since Wednesday.

She said the school was supporting the family and working on an appropriate way to remember Ms Vukotic.

Thousands of people joined a tribute page established on social media in honour of the teenager, with hundreds of people leaving messages of condolence to the family.