Inmates riot at WA youth detention centre

West Australian Premier Mark McGowan says there will be an inquiry into the latest riot at a Perth youth detention centre, in which staff locked themselves in rooms for safety.

The riot at Banksia Hill Detention Centre on Thursday night took two hours to control and resulted in injuries to three inmates

It started with five youths, aged between 15 and 18, damaging their living area before escalating.

Fires were lit and more youths joined in, resulting in staff using flash bombs and pepper spray to try and control control the youths.

One teenager got hold of a nine kilogram gas cylinder, prompting fears of a bigger fire.

All staff were safe and uninjured, but three youths suffered minor injuries - an asthma attack, a cut leg and an eye injury caused by glass.

There were a string of ugly incidents at Banksia Hill in the second half of 2016, including one in which a prison officer's arm was broken and elbow dislocated while trying to control an inmate.

Mr McGowan said it was happening far too often.

The Community and Public Sector Union says WA needs more than one youth detention centre and Mr McGowan has not ruled out reopening Rangeview Juvenile Remand Centre, which closed in 2012, leaving only Banksia Hill.

"We need to get to the bottom of what's going on here. This is happening way too often," he told reporters on Friday.

A riot in January 2013 left the Department of Corrective Services with a $1.5 million bill after close to half the cells at the centre were trashed when 60 youth escaped from their rooms.

The facility was virtually destroyed and detainees were transferred to an adult high security prison, before the centre reopened in September 2013.

CPSU WA secretary Toni Walkington blames a "no consequences" policy and rehabilitation focus, putting young people and their interests foremost, which came out of a 2015-2018 WA Youth Justice Framework.

"There is a need for very basic consequences such as detainees having their TV taken away, or losing their gratuities for small misbehaviours," she said.