The reason for the killing late last night was because the labourers had just received their wages, the sources said.
Inspector General (Western Range) H Nongpluh confirmed the killings and said that he was awaiting details.
The sources said the police have rushed to the spot.
Condemning the killings, Chief Minister Mukul Sangma said that perpetrators would be punished.
The killing of the labourers followed last Friday's lynching of a migrant labourer from Assam's Dhubri district by a mob after he was allegedly caught caught harassing a mentally unstable girl with four of his friends in Tura town in the West Garo Hills.
The state government had paid Rs 3 lakh as compensation to the family of the labourer who was lynched.