The girl and a 23-year-old man were arrested in Leader, Saskatchewan, a day after the bodies of an adult couple and a young boy were found in a house in the southeastern Alberta community.

The two people arrested have both been charged with three counts of first degree murder.

Police did not speculate on a motive for the killings or say if the girl was related to the victims -- whose names were also being kept confidential.

Investigators said the victims had had no previous dealings with police, and residents of the area told local media the family had been good neighbors.

The male suspect, Jeremy Steinke, also of Medicine Hat, was known to police, investigators said. The girl cannot be named because of her youth.

Police said they were still searching for a truck that was believed to be linked to the incident.