Jasmine Vuong and her friend Anthony Nguyen, both 17, were mowed down by an SUV while crossing the intersection of Taylors and Braeswood roads about 11.30pm on Tuesday.

Anthony, who suffered severe head injuries, died in the intensive care unit at the Royal Melbourne Hospital on Wednesday evening.

Jasmine remained in a critical condition in the same hospital on Thursday afternoon. She has undergone surgery for a fractured skull. The 17-year-old is also suffering multiple broken bones, including a broken arm and a broken hip.

Police arrested the Hillside man at his home on Thursday afternoon. A car, which matched a description given earlier on Thursday by police, was also found at his house.

Another person is assisting police with their inquiries.

"We also have another person who is providing us with significant information about the actual incident and the aftermath of it," Detective Inspector Bernie Rankin said.

"It's been very good investigative work by people from Victoria Police."

Earlier, Jasmine's mother Suong Phung  asked how someone could leave her teenage daughter lying bleeding and seemingly lifeless in the middle of the road without so much as pausing to call triple-0.

"Their lives were reliant on that call and he ... not make any call to save their lives and he just run away," Ms Phung said.

The teens had just stepped onto the road on a green pedestrian signal when they were hit by a car running a red light.

The driver did not stop, leaving the two teens for dead, both with critical head injuries.

Neighbours reported hearing a bang and seeing two bodies lying on the road.

"They didn't move. They did not move," one resident told Seven News.

A heavily pregnant Suong Phung received a knock on her door from police at midnight.

"They said it's a hit and run and ... we have to prepare ourselves," she told reporters.

The teenagers' shoes, surrounded by debris from the car, including pieces of the car's broken headlights, were all that remained at the scene on Wednesday morning.

Police determined that the pieces of the headlight recovered at the scene belonged to a light-coloured Nissan Dualis SUV, manufactured between October 2007 and January 2010.

The SUV was also captured in Delahey on a nearby resident's CCTV camera.

Detective Inspector Bernie Rankin said there were no signs that the driver had tried to avoid the teenagers.

"They've been propelled a fair distance, which means the vehicle was travelling at a reasonable rate of speed prior to the crash. There's no signs of skidding, no signs of evasive action," he said.

"The damage is extensive enough that it's not possible the driver hasn't realised they have hit someone.

"For someone to hit two teenagers and then leave without attempting to help them is disgraceful."

Jasmine was due to start year 12 at Copperfield College on Thursday.

Principal Tony Simpson said the impact of the tragedy would be far-reaching among students and the wider Vietnamese community. It is understood Jasmine's younger siblings and cousins also attend Copperfield.

He said critical incident teams from the Education Department were on all three campuses of Copperfield College.

"There is support and counselling available for friends and family," he said.

Anthony left Keilor Downs College in September to take up an apprenticeship as a motor mechanic in Deer Park.

His distraught parents have released a statement thanking the community for their thoughts and support.

Keilor Downs College principal Stuart Andrews said counsellors had been called in to support distraught students and parents.

"A lot of people have been touched by what's happened - it's not just students who were close to him," Mr Andrews said.

"Anthony was always having a laugh. He just never seemed to frown. He was always friendly to everybody ... the life of the party."

Mr Andrews said Anthony found his passion after undertaking a Certificate of Applied Learning in motor mechanics.

"He just blossomed, he flourished and found his passion in life," Mr Andrews said. "He was overjoyed when he was offered a full-time apprenticeship ... and was able to realise his goal of becoming a motor mechanic."

Orlando Nguyen paid tribute to his friend Anthony on Facebook, remembering him as the "funniest person" he knew.

"It sucks to hear that you will no longer be with us and that there are cruel people in this world to let that happen," he wrote.

"[You] could always brighten up a boring situation and put a smile on everyone's faces. You'll never be forgotten, rest easy up there brother."

Road policing Assistant Commissioner Robert Hill said he could not comprehend the merciless actions of the driver.

"I cannot understand why a motorist, having struck two pedestrians, would not stop to render assistance," he said.

"It is morally just a disgrace, in my mind."

Anyone who witnessed the incident or who may have further information is asked to contact Crime Stoppers on 1800 333 000.