Sydney, July 22 -- Several inmates have been stabbed during an ongoing riot at an Australian juvenile detention center, police said Monday.

Police were negotiating with the inmates and hoped the standoff could be resolved without further injuries, Police Superintendent John Gralton said.

The riot at the detention center north of Sydney started at 8.30 p.m. on Sunday. Eight inmates surrendered by Monday afternoon but another 12 had not, he said.

The union representing the guards said inmates stole keys from an officer and took garden tools, including a hedge trimmer and shovels from a maintenance shed. Public Service Association general secretary Stewart Little said the group targeted known sex offenders.

"It seems a very sudden and un...