Paramedics treated 10 women and seven men, ranging in age from 20 to 69, for soft tissues injuries, fractures and lacerations.
They were taken to Box Hill, Austin and Maroondah hospitals.
Another dozen people were assessed at the scene and did not require hospital treatment.
"This is a very tragic incident for those involved and our thoughts are with them and their loved ones at this time," Mr Holman said.
It is understood furniture, including a fridge and barbecue were on the balcony at the time of the collapse.
All emergency services attended, including SES, CFA, MFB, police and paramedics.
Leading Senior Constable Melissa Seach said in a statement that emergency services were called to a house on Balinga Court about 10.30pm.
"It is believed more than 30 people were standing on the balcony when it collapsed," she added.
"A woman, who is yet to be formally identified, died at the scene. A woman aged in her 30s, received life-threatening injuries and was taken to hospital.
"It is believed 17 other people were injured and taken to hospital.
"Police are currently on scene investigating the circumstances surrounding the incident."
Acting Superintendent Kerin Moloney said the tragedy was "magnified by the fact that we're only a week away from Christmas".
Supt Moloney said counselling had been offered to all personnel who attended the horrific scene.
"It was a really tragic incident for all emergency services who have attended and also those who were present at the party," he said.
"All the police that have attended have been offered peer support and also the SES and ambulance officers."
Video and photos from the scene show dozens of fire trucks, ambulance vehicles and police in the small court.
A witness posted online saying there were "walking wounded" being helped in the street and firefighters were helping paramedics treat patients.
Victoria Police had taken control of the scene early this morning.
The Sunday Herald Sun understands the victims were celebrating at a work Christmas function.
Dozens of police and SES were on scene as investigators gathered evidence.
Shell-shocked neighbours watched from across the street.
An off duty police officer, who wished to remain unnamed, was at a neighbouring house when people came knocking on the door for help.
"I've had better days," he told the Herald Sun.
Neighbour Judy said she was asleep when she heard noise in the street.
"There were a lot of cars, a lot of noise," she said.
"A lot of people were running around the street carrying pillows, I didn't know what was going on."
"I couldn't sleep, it was very loud.
"There was lots of sirens wailing and lights flashing."
One man, who asked not to be named, said he was stunned by the tragedy.
"This is just a typical quiet eastern suburbs neighbourhood," he said.
Neighbour Dennis said he returned home from a night out in the city to find his street completely blocked off.
"I live opposite the house (where the collapse occurred), the police said I can't go back inside yet," he said.
Shivering against the cold, Dennis said he had "never seen anything like this".
