Fracas at WA juvenile detention centre

Stun grenades and pepper spray have been used on four detainees at Perth's juvenile lock-up centre who had makeshift weapons behind a barricade.

The group barricaded themselves in a wing of the Banksia Hill juvenile detention centre on Thursday afternoon.

The Department of Corrective Services says its special operations group were brought in to manage the incident after attempts to talk to the youths failed to de-escalate the matter.

"The youths had makeshift weapons and access to hot water which could have been used against staff and themselves," the department said in a statement.

A one-second shot of pepper spray was fired at the barricaded door and three flash bangs were released.

"The incident was resolved with no injuries," the department said.

The matter has been referred to WA police and an estimated cost of the damage has not been finalised.

According to the CPSU/CSA, the union representing the centre's workers, the youths were aged 17 and 18 and had smashed windows and pulled doors off cupboards, the fridge and oven.

The centre was in lockdown from 12.55pm to 2.30pm.

It is the second incident at the centre this week.

Another incident at the centre on Monday caused $50,000 damage, the department said.