A freak accident involving an inflatable jumping castle has resulted in the deaths of four children. Authorities said an inflatable castle was lifted into the air more than 30 feet by a strong gust of wind on Thursday. Five other children had to be sent to the hospital after suffering serious injuries.

The accident occurred at the Hillcrest Primary School in Devonport, on the island of Tasmania in Australia. Officials said Thursday was the last day of school for the children, which is why they were celebrating on the school's grounds.

Police said nine children were inside the inflatable jumping castle when it was lifted by the wind at around 10 a.m. in the morning local time.  Ambulances were immediately dispatched to the scene, which then brought the injured children to the nearest hospitals.

Tasmania's police commissioner, Darren Hine, told reporters that two girls and two boys had died from their injuries after falling more than 30 feet. Hine said the four other children are now in critical condition after sustaining serious injuries.

Hine did not say if the jumping castle was properly tethered to the ground when the incident happened. He only stated that they are still conducting an investigation into the matter together with the state's health and safety regulator.

Devonport is a tiny city in northeast Tasmania with a population of around 23,000 people. Hillcrest is one of the city's six elementary schools, located on the outskirts. The school program, which was scheduled to begin at 9:30 a.m., included activities such as a slippery slide, dancing, and arts and crafts, as well as a jumping castle.

After the incident, the school published a post on social media stating that it would be closing down for the rest of the day. It also asked parents to come to the school to fetch their children as soon as possible immediately.

Prime Minister Scott Morrison published a post on social media expressing his condolences to the families of the victims. Morrison described the events as "unthinkably heartbreaking."

Inflatable jumping castles have claimed the lives of dozens of children in the past. In 2019, two children died, and 20 others were injured after a strong gust of wind swept a jumping castle into the air in Henan, China. In 2018, a child was killed after he was thrown off a jumping castle. In 2016, two fairground workers in England were arrested and charged after a jumping castle was blown away and killed a 7-year-old girl.