The clash began after police cracked down on MIPRL members, who were blocking NH-6 on Wednesday to press for their demands. Two persons, including a woman, died in the scuffle.
Curfew, which was imposed on Wednesday evening after the clash, has been withdrawn. Two companies of BSF have been deployed in East Jaintia Hills district. The state government has asked the security forces to maintain vigil along the entire stretch of NH-6 (formerly known as NH-44) that passes through the state.
SP M K Dkhar was injured in the clash.
Meghalaya chief secretary PBO Warjri said the state government is aware of the "crucial nature" of NH-6, which serves as the lifeline for Tripura, Mizoram, Cachar Valley and western Manipur.
"Steps are being taken to ensure there is peace along the highway," Warji said, adding that precautionary measures and "quick action" would be taken to maintain law and order. He added nobody would be allowed to disrupt movement of people and goods within the state.
Pointing out that the mob had attacked police with "various kinds of weapons", the chief secretary said an inquiry is on to determine the exact nature of the scuffle.
Meanwhile, there has been no inter-state movement of vehicles along the highway, as the blockade entered its third day on Thursday, IGP (law and order) GHP Raju said.
He said their demands for ex gratia and jobs have been heard by the deputy commissioner and would now be placed before the state government.