Andrew Stone was inside his home in Doncaster East about 9.30 when he heard the crash.

"I ignore a lot of noises that you hear in the neighbourhood and the sound of that balcony crashing got me right up and out of the chair," Mr Stone said.

"At first, I thought maybe a fight or something had broken out. I heard crashing. In hindsight, it was maybe five seconds long but it felt like forever."

Eve and Chris Nunn, owners of a Tupperware distributorship, had been hosting a Christmas party for team members at their rented home in Balinga Court when the timber balcony collapsed. Ms Nunn is believed to have been among the injured.

A photo from the couple's 2016 Christmas party could be seen on Ms Nunn's Facebook page, with almost 30 people posing on what appears to be the same balcony.

The post was deleted on Sunday afternoon. The Age has chosen not to publish the photo.

More than 30 people were believed to have been standing on the balcony on Saturday night when the flooring gave way.

The railing remained intact, but there was a gaping hole in the flooring where the boards collapsed beneath the feet of party guests.

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Paramedics described the scene as "chaotic".

Furniture including a barbecue and a fridge were on the balcony when it collapsed.

Ambulance Victoria activated its major emergency response plan, using more than a dozen ambulances to move the injured to several hospitals.

A 59-year-old Croydon woman died at the scene. A 37-year-old Reservoir woman was taken to Royal Melbourne Hospital, where she died on Sunday morning.

A further 10 women and seven men, ranging in age from 20 to 69, sustained soft-tissue injuries, fractures and cuts. They were taken to Box Hill, Austin and Maroondah hospitals.

On Monday morning two patients remained in hospital, on at Box Hill and one at Maroondah. Both were in a stable condition.

A number of people were trapped, Metropolitan Fire Brigade spokeswoman Belle Nolan said.

Mr Stone said the incident was "loud, really loud".

"The sound of it was sharp. It was like a tree being felled. The crash was biblical," he said.

"The sound of it was nothing like I had heard before and, of course, followed by screaming. It was fairly intense."

Mr Stone said he went outside and saw other neighbours there, some coming to people's aid with blankets and chairs.

"That's when I heard someone really hysterical on the street dialling triple zero," he said.

One of the police officers told him the partygoers had been on the balcony to take a group photo, he said.

"Really devastating," Mr Stone said.

"[The residents] are a lovely couple ... They obviously hold Tupperware parties fairly often.

"It's not something you think about: the balcony. That sort of thing doesn't happen in Doncaster East."

Another neighbour said a "very nice" couple lived in the house with their daughter.

The large brick veneer house is at least 20 years old and is rented.

Flowers were laid outside the home on Sunday and shocked residents said they were coming to terms with the tragedy.

Neighbours said they comforted victims, bringing them towels and blankets and inviting them into their homes to clean up.

Dima, 16, said one woman and a man with a limp came into her home, directly next to the scene of the accident, to use her bathroom.

"[The woman] was very traumatised, very shaken up, it seemed her breath was not like normal from shock," Dima, who requested her surname not be published, said.

She said the woman, who had a bandage on her arm and was "in a bad state", described the events which led to the accident.

"They were having a Christmas party and when they went to take a photo on the balcony, all of a sudden, whilst they were taking pictures, it just fell," she said."They had a fridge on the balcony, and when the balcony fell so did the fridge ... She was drenched with, I suppose, the alcohol that had fallen with the fridge.

"Some people were beneath the balcony ... She said she had fallen on top of people, she said people were struggling to come out."

One of the property's owners said on Sunday afternoon that the house had been in good condition when his family lived there between 2010 and 2014.

"We were enjoying it," he said. "We didn't notice anything damaged or any cracks."

The man, who asked not to be identified, said he had lived in the Balinga Court property with his wife and two children.

The home was listed for sale last year but did not sell and was rented out to the current tenants.

The man said the balcony was in good condition, but it was just a wooden deck.

"It's not very big," he said.

"I was just wondering how you squeeze 30 people on the balcony? You got an average weight of a person, say 70 kilograms. Multiply that with 30 people, that's 2.1 tonnes. A car weighs 1.6 tonne."

The man said he heard about the accident on Sunday morning when the property agent called.

"I was very sorry to hear it," he said. "It's just one week away from Christmas."

On Sunday morning, Christmas lights were still blinking at the entrance of the house. Giant blow-up Santas decorated the lawns and a few deflated Santas lay on the garden beds.

Inside the empty house, a light had been left on. Two Tupperware company cars were in the driveway.

Daisy Chin-Lor, president of Tupperware and Nutrimetics Australia and New Zealand, said the accident involved members of the Nunns' team.

"We want to express our deepest condolences to the families who have lost a loved one," she said.

"Our thoughts and prayers are with them and with the others affected and their families. We continue to offer our support and comfort as we learn more details of the accident."

Police and the State Coroner remained at the scene on Sunday afternoon.

State Health Commander Paul Holman said the incident was tragic for those involved.

"Our thoughts are with them and their loved ones at this time," he said.

Premier Daniel Andrews said he had spoken to officials from his department and there would be a "proper investigation" into the incident.

"Our hearts go out to the families of those two people who have lost their lives," he said. "This is a terrible incident."