THE parents of siblings Alexander and Bridget Jones have said they are ''overwhelmed'' and ''distressed'' after their son died and their daughter battles for life in hospital following the wall collapse in Carlton on Thursday.

Ian and Sue Jones issued a statement this afternoon to thank everyone who tried to help in the tragedy.

''We are overwhelmed at the loss of our son Alexander and are very distressed to see our critically ill daughter in the hospital.

''Our hearts go out to the family of the other lady who was killed in this tragedy.

''We understand people who were passing by and the emergency services did everything that they could and we are so grateful these people tried their best for our children.

''We would also like to thank members of Victoria Police and staff at The Royal Melbourne Hospital who have been so caring and respectful.

''We would like to thank our family and friends and the friends of Alexander and Bridget, the Montmorency Secondary College community, and many others who have sent in their wishes and offered support.

media_camera Brother and sister Alex and Bridget Jones were devoted to each other.

''We would ask that people respect our privacy at this very sad and difficult time,'' the statement read.

Melbourne University architecture student Alex Jones, 19, was walking sister Bridget, 18, along Swanston St to her 3pm class when a powerful wind gust brought a brick wall crashing down on top of them.

Rescuers on the scene immediately afterwards said Mr Jones's body was found on top of his injured sister, partially shielding her from the crushing impact.

Dozens of friends today gathered at the collapsed wall at the Grocon site on Swanston St to lay flowers and console one another.

Bridget remained fighting for life at the Royal Melbourne Hospital after emergency surgery.

Her brother, and an unidentified woman in her 30s, died instantly.

Grieving friends paid tribute to Alex.

Jorja Shae Carter-Smith posted on Facebook: "Zander, a true hero. I know you would have done this to protect your much loved sister, being the gorgeous soul that you were."

Another friend, Bethan Wainman, spoke through tears as she lamented the loss of a ''Mr Nice Guy'', known as ''Zander'' to his mates.

"They were very close and loved each other very much,'' Ms Wainman told the Herald Sun.

"He was an amazing guy and no one had anything bad to say about him.

"He was very funny, jovial, and would always laugh and play around."

media_camera wall collapse

Zoe Liberona posted on Facebook: "Such a beautiful soul taken way too soon. Rest in peace, Alexander Jones."

Callum Fuller added: "Still in absolute shock. Rest in peace, Alexander Jones."

School friend Steven Kostadinovski said of the former school captain: "Much love to a great human being and individual.

"It was a pleasure to be a part of your life, big fella. Will be missed."

And Matt Perichon said: "It is just so cruel how life can be torn away from such a beautiful young man."

Mourners left flowers, a teddy bear and a Lindt chocolate carrot at the scene of the tragedy.

media_camera Alex Jones, 19, died in the Swanton St wall collapse, and his sister, Bridget, 18, is fighting for her life.

Emergency talks will be held next week to determine how and why Thursday's deadly wall collapse happened - and ensure a similar accident never recurs.

WorkSafe, the State Coroner, Victoria Police and Grocon have all launched independent investigations into the incident.

The remainder of the wall was demolished late on Thursday night.

Wire fencing was erected to protect the public from a rubble of bricks and debris still littering the site.

Red brick dust still covered the footpath.

Melbourne north Crime Investigation Unit's Detective Senior Constable Brooke Manley said police had notified known affected families.

media_camera Flowers were laid at the scene of the tragedy this morning. Picture: Stuart Walmsley

"It's horrendous - a tragic accident," she said.

"The families involved are devastated."

Police believe more people were injured in the collapse, but fled the scene fearing further harm.

Banyule Mayor Wayne Phillips said the council would offer any support possible to the Jones family, of Montmorency.

It was to be hoped the tragedy was a freak accident and not the result of red tape, he said.

"If it's a freak accident it's very sad," he said.

"But if it's something structural - or something caused by the fact there are heritage restrictions, and they have been demolishing parts of the site around it and the wall was not properly supported - that would be a tragedy," Cr Phillips said.

Next week's talks will involve the State Government, Victorian Building Commission and Melbourne City Council.

Planning Minister Matthew Guy told the Herald Sun he had ordered the Building Commission audit in a bid to prevent similar tragedies.

"We will get the Building Commission to look at all those CBD structures as soon as possible," the minister said.

Mr Guy said he would also seek advice on structural tests and see if they could be carried out more frequently.

"This one has passed the structural strength for some time and that's fine.

"But it's whether or not it remains at that level," he said. "There needs to be a continual audit and continual compliance for structures that are like that."

City of Melbourne spokesman Sam Bishop said: 'If concerns are raised about the integrity of any particular structure in the City of Melbourne, our municipal building surveyor's office will investigate."

The collapse of the wall at the CUB brewery site in Swanston, St, Carlton, is believed to have been caused by a freak gust of wind.

Grocon officials believe the wall was built in the 1970s, forming part of a boundary to the CUB site.

With Peter Rolfe

Additional reporting: Christopher Gillett, Jon Kaila, James Dowling and Jessica Evans

Originally published as Wall tragedy parents thank strangers