What started as a youthful celebration ended in tragedy at an elementary school in Australia.

Children and staff at the school in Devonport, Tasmania, were enjoying their last day of the school year with a morning of fun activities.

But the festivities were brought to an abrupt and shocking end when heavy winds swept a bouncy castle into the air — and then sent nine children plunging to the ground, killing five and seriously injuring four.

In a statement, police said the nine students at Hillcrest Primary School had fallen from a height of around 10 meters (32.8 feet) after a “significant local wind event” caused the jumping castle and several inflatable “zorb” balls to lift into the air.

The incident happened at around 10 a.m. local time (7 p.m. E.T. Wednesday), Tasmanian Police said, with officers and emergency services, including two helicopters, racing to the scene within two minutes and beginning to administer first aid.

“Sadly, four children — two girls and two boys — died and another five suffered critical or serious injuries and are in hospital,” the island state’s police department said in an initial statement.

Hours later, police confirmed to NBC News that a fifth child had died. They said they could not provide any updates on the condition of the four other children hospitalized.

Police said the students were in grades 5 and 6, which means they were likely between the ages of 10 and 12.

News of the incident was met with an outpouring of grief from across the country.

“On a day where these children were meant to be celebrating their last day at primary school, instead we are all mourning their loss,” police Commissioner Darren Hine said in a statement.

“Our hearts are breaking for the families and loved ones, school mates and teachers of those children taken too soon,” Hine said.

Support and counseling was being made available to all of those involved, including to emergency service workers, Hine said.

Australian Prime Minister Scott Morrison described the incident as “shattering and heartbreaking.”

“Young children on a fun day out, together with their families and it turns to such horrific tragedy at this time of year. It just breaks your heart,” Morrison told reporters.

Tasmanian premier Peter Gutwein said it was “simply inconceivable that this shocking tragedy has occurred” and promised a thorough investigation.

An investigation into the incident is underway, with WorkSafe Tasmania, the state’s work health and safety regulator, involved in the probe, police said.

Davenport is a small port city on Tasmania’s northern coast.

The tragedy in Tasmania is not the first such incident to unfold in connection with a jumping castle.

In May, four children were injured after a bouncy house was lifted by strong winds in Arizona.

In 2015, a young girl in southern China died after falling from a bouncy castle that was blown into the air by a strong gust of wind.