Four children were killed and several more badly injured in Australia after strong winds lifted an inflated jumping castle into the air during end-of-year school celebrations, causing them to fall 10 metres , authorities said on Thursday, prompting an outpouring of grief.

Two boys and two girls in their final year of primary school died in the accident in Devonport, in the northwest of Tasmania state, about 2300 GMT on Wednesday. Five more children were in hospital, four in critical condition.

There was no immediate explanation for how the jumping castle became airborne, and no other details were released of the children’s identities except that the incident took place at Hillcrest Primary School. Students in the last year of primary school, Year 6, are typically aged 10 or 11.

The accident would rank among Australia’s deadliest involving an amusement ride.