Parents of students at Tasmanian primary school recall horrific scenes after jumping castle incident

The inflatable device flew several metres into the air in a gust of wind. Photo / ABC News

Parents have recalled the gut-wrenching moments they had to wait at the entrance of Tasmania's Hillcrest Primary School unsure if their child had been involved in a fatal jumping castle incident.

Four children — two boys, two girls — died and five others are in a critical condition after a jumping castle they were playing on flew several metres into the air.

In the hours that followed the tragedy, stressed parents were reportedly forced to wait at the school gates with no information on whether their children had been injured.

Some took to social media panicked about being kept in the dark.

One mum wrote on Facebook that she arrived at the school about 11.30am but she and other parents were not being allowed in.

"I'm here now they won't let us in, it was [child's name] grade no one knows who was hurt yet," she wrote.

Another said their friend whose child attended the school had yet to hear anything.

"What grade is it believed to be? I have a friend with children there and he hasn't heard anything yet," they said.

A mum whose child attends a different school drove to Hillcrest to support a friend, but arrived to what she recalled a "horrific" scene.

"I went there because a friend was upset trying to figure out if their kids were okay before she got there and it was just horrific," she wrote in a comment.

A man said he watched as crews desperately tried to save the life of one of the children.

"I was there and the emergency response crew were trying so hard to revive the first child ... I'm positive they couldn't do anything more. Very sad," he wrote to Facebook.

Heartbroken police officers comforted each other at the scene. Photo / ABC News

Adults responsible for another little boy feared if they hadn't dropped him off late for school that morning, they may have received a different call.

Police urged the public to stay away from the school following the incident, with two rescue helicopters and multiple ambulances having been deployed to the scene.

A young schoolboy who witnessed the horrific incident said he narrowly missed out on getting on the ride.

"It was our turn next," he told The Mercury. "Grade five and six went first."

The school on social media asked parents to collect their children "as a matter of urgency".

"There has been an accident onsite at our school. We are closing the school for the rest of the day," its post read.

Tasmanian police said "several children fell from a height of about 10 metres" after a "wind event" caused a jumping castle to lift into the air.

Prime Minister Scott Morrison has described the incident as "unthinkably heartbreaking".

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

"And I just want to say, on behalf of all Australians, to the parents and families and friends, all who were there, to the other young children there and witnessing these events, I just pray you'll have great family around you and great friends and you can come through this horrific tragedy."