The children fell about 10m (32ft) after a wind blew the castle skywards at a Tasmania school fair on Thursday.
Police identified the victims as 11-year-old Addison Stewart, and 12-year-olds Zane Mellor, Jye Sheehan, Jalailah Jayne-Maree Jones, and Peter Dodt.
Three other children remained in a critical condition on Friday.
Another injured child has been discharged from hospital.
Police said the parents of the victims did not wish to speak publicly, but other relatives have given tributes online.
Peter Dodt's aunt Tamara Scott wrote the young boy "was full of life and adventures".
An aunt of Addison Stewart, Meg Aherne, said: "I don't even know what to write at this stage. Everyone is devastated, she was always such a sweet, kind, old soul."
Zane Mellor was described by a family friend as a "gorgeous boy" and a "beautiful, caring, gentle soul".
Mourners leave flowers in front of Hillcrest Primary School
IMAGE SOURCE,EPA
Image caption,
Davenport residents have left flowers, soft toys and other tributes in front of the school
Mr Morrison called it a "terrible tragedy" and said "as a parent there are no words".
The accident at Hillcrest Primary School has shattered Devonport - a city of fewer than 30,000 people.
There would be "few people if any in Devonport that would haven't had a connection to one of those families, to that school", Mr Morrison said.
Investigation under way
It's still unclear how the incident unfolded on a mostly calm and sunny day.
Australia's weather bureau recorded wind speeds between 7km/h (4mph) and 22km/h on Thursday morning - a range considered average.
Police said they would investigate whether the bouncy castle was tethered to the ground.
"We all have a lot of questions," said Tasmania Police Commissioner Darren Hine.
About 40 students from grades five and six had been taking part in the school fun day.
Teachers and other adults rushed to administer first aid before paramedics arrived, police said. Other pupils nearby were shepherded away.
"What should have been a celebration for the end of the school year turned into an unfortunate tragedy for our young children," said Tasmania's Premier Peter Gutwein.
Media caption,
Australian PM: “It just breaks your heart”
A online fundraiser for the families has already raised A$600,000 (£323,000; $430,000).
There have been other fatal bouncy castle incidents. In 2019, two children were killed and 20 others injured in a similar accident in China.
A year earlier, a girl died in the UK after being thrown from a bouncy castle that eyewitnesses say exploded on a Norfolk beach.
And two fairground workers were jailed for manslaughter by gross negligence after a bouncy castle blew away with seven-year-old Summer Grant inside, in Essex, in March 2016.
The children fell about 10m (32ft) after a wind blew the castle skywards at a Tasmania school fair on Thursday.
Police identified the victims as 11-year-old Addison Stewart, and 12-year-olds Zane Mellor, Jye Sheehan, Jalailah Jayne-Maree Jones, and Peter Dodt.
Three other children remained in a critical condition on Friday.
Another injured child has been discharged from hospital.
Police said the parents of the victims did not wish to speak publicly, but other relatives have given tributes online.
Peter Dodt's aunt Tamara Scott wrote the young boy "was full of life and adventures".
An aunt of Addison Stewart, Meg Aherne, said: "I don't even know what to write at this stage. Everyone is devastated, she was always such a sweet, kind, old soul."
Zane Mellor was described by a family friend as a "gorgeous boy" and a "beautiful, caring, gentle soul".
Mourners leave flowers in front of Hillcrest Primary School
IMAGE SOURCE,EPA
Image caption,
Davenport residents have left flowers, soft toys and other tributes in front of the school
Mr Morrison called it a "terrible tragedy" and said "as a parent there are no words".
The accident at Hillcrest Primary School has shattered Devonport - a city of fewer than 30,000 people.
There would be "few people if any in Devonport that would haven't had a connection to one of those families, to that school", Mr Morrison said.
Investigation under way
It's still unclear how the incident unfolded on a mostly calm and sunny day.
Australia's weather bureau recorded wind speeds between 7km/h (4mph) and 22km/h on Thursday morning - a range considered average.
Police said they would investigate whether the bouncy castle was tethered to the ground.
"We all have a lot of questions," said Tasmania Police Commissioner Darren Hine.
About 40 students from grades five and six had been taking part in the school fun day.
Teachers and other adults rushed to administer first aid before paramedics arrived, police said. Other pupils nearby were shepherded away.
"What should have been a celebration for the end of the school year turned into an unfortunate tragedy for our young children," said Tasmania's Premier Peter Gutwein.
Media caption,
Australian PM: “It just breaks your heart”
A online fundraiser for the families has already raised A$600,000 (£323,000; $430,000).
There have been other fatal bouncy castle incidents. In 2019, two children were killed and 20 others injured in a similar accident in China.
A year earlier, a girl died in the UK after being thrown from a bouncy castle that eyewitnesses say exploded on a Norfolk beach.
And two fairground workers were jailed for manslaughter by gross negligence after a bouncy castle blew away with seven-year-old Summer Grant inside, in Essex, in March 2016.
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