The RCMP and other Saskatchewan authorities have released more information about the beating death of a six-year-old boy east of Regina, saying that another boy under the age of 12 is believed to be responsible.

RCMP said Tuesday the boy was apprehended at the scene of the beating death of Lee Bonneau, 6.

Bonneau's body was discovered Aug. 21 in an open area behind a recreation centre on the Kahkewistahaw First Nation, a community of 600 people located about 150 kilometres east of Regina.

"Because the person investigators believe is responsible for this homicide is under the age of 12, the child cannot be charged under the Youth Criminal Justice Act," RCMP Staff Sgt. Larry Brost told news reporters Tuesday.

Brost said Bonneau died of a head trauma.

Information obtained by CBC News and confirmed by officials Tuesday shows the child believed responsible was considered a troubled boy who was known to be "violent and unpredictable."

CBC News also learned a weapon was used, but Brost said investigators were still trying to determine what that weapon was.

RCMP said no one else was involved in the death.

"There's no other person at this point in the investigation that could be responsible for this other than this child," Brost said.

When asked about why the boy attacked the other child, Brost said police did not have an immediate answer.

"This is a unique case," Brost said. "We may never find that answer."

Lee Bonneau, 6, was described as a fun-loving boy who loved to be outdoors. (RCMP)

The day of his death, Bonneau was at a community centre with his foster mother for Wednesday night bingo. She last saw him playing with a group of dogs outside, then he vanished.

After a 90-minute search, Bonneau was found with severe head injuries, and was rushed to hospital where he was pronounced dead.

He had been placed in foster care three weeks prior to his death.

The RCMP said Bonneau's biological mother described her son in a statement as "a fun-loving boy on his way to Grade 2, who had the deepest laugh and loved being outdoors."

Because the child believed responsible is under the age of 12, he cannot be charged under either the Criminal Code or the Youth Criminal Justice Act.

The boy is currently in the care of social services.

On Tuesday an official from the Ministry of Social Services said the boy was being assessed to determine what sort of treatment he needs.

"Those treatment needs are going to change as he grows older," said Andrea Brittin, an assistant deputy minister in the social services ministry. She added that the ministry and Yorkton Tribal Council child and family services agency will have to work together.

Brittin said the nature of the case means the boy is automatically deemed to be "a child in need of protection" because of an offence that would have resulted in charges under Criminal Code if he were 12 or older.

According to officials, the child now in the ministry's care could remain closely supervised by social workers until he reaches the age of 16 and possibly until the age of 21. In order to keep the child beyond the age of 16, officials would have to follow provisions of the province's Mental Health Act.

On Tuesday, Saskatchewan's Minister of Social Services June Draude said she has requested an immediate review of the case by the province's children's advocate. That review is in addition to an internal review by the ministry, Draude said.

Police said the child believed responsible for Bonneau's death was living in a foster home just on the edge of the First Nation, but not on reserve land. The two youngsters did not know each other, according to RCMP.

Community considers curfews

"The community is shocked. The community is overwhelmed," Chief Sheldon Taypotat said Tuesday. "We're working together to ... help each other heal."

Taypotat added that council members were considering curfews for the community.