Two inmates at a youth detention centre in Australia’s Northern Territory stole keys from a staff member and then released detainees, sparking a riot at the facility. A group of inmates then set the facility’s school on fire and attempted to break thorough fences using power tools, The Guardian reported on Wednesday.

The incident took place at Don Dale Youth Detention Centre in Darwin city on Tuesday. At least 15 police cars, firefighters and ambulances rushed to the centre around after receiving calls of a disturbance at the facility. The police took more than seven hours to find the detainees who had tried to escape. All 25 inmates of the facility have now been moved to cells at the Darwin police station watch.

Northern Territory Police Duty Superintendent Rob Farmer said some youngsters had stolen power tools, including angle grinders, from the workshop in order to cut the fences. The Territory Response Group used tear gas to quell the disturbance. “They weren’t actually affected by the gas,” said Farmer, according to The Australian.

This is the second time in a month that detainees have caused a disturbance by stealing keys.

Northern Territory Police’s Specialist Services Commander Matt Hollamby and Territory Families General Manager of Youth Justice Brent Warren said a part of the problem is that the facility was formerly an adult prison and not for accommodating or rehabilitating children, reported ABC News.

“Territory Families inherited an adult prison that was retired a number of years ago,” Warren told The Guardian. “We are trying to make do with what we’ve got. We have invested a significant amount of money changing the nature of the facility to make it look and feel more suitable for young people in detention.”