Four children have died and five others are injured after falling from a bouncy castle that was blown into the air in Australia, police say.

The accident - caused by a wind gust - happened on Thursday at a primary school fun day in Devonport, Tasmania.

Police said the children had fallen from a height of about 10m (32ft).

Authorities have not given ages for the children but said two boys and two girls had died.

Tasmania Police Commander Debbie Williams described the scene as "very confronting and distressing".

"It appears a wind gust caused the castle to lift into the air," she told reporters outside Hillcrest Primary School.

Australian Prime Minister Scott Morrison described the accident as "unthinkably heartbreaking".

"Young children on a fun day out… and it turns to such horrific tragedy. At this time of the year, it just breaks your heart," he said.

Paramedics arrived quickly at the scene after the accident at about 10.00 local time (23:00 Wednesday GMT).

The children were given first aid before being flown in helicopters to hospital.

Parents were alerted immediately following the incident, which happened on the last day of the school year.

ABC reporter Monte Bovill tweeted that locals "have been running to the school to collect their children".

State Premier Peter Gutwein said authorities would give further updates later on Thursday.

"As this involves a primary school, thoughts are obviously with the people involved [and] obviously the parents of the children that have been injured," he said.

Devonport, on Tasmania's northern coast, is a small port city with just under 30,000 residents.

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.