Some 11 people were killed and six others sustained injuries in violent clashes which broke out between police and tribals Tuesday, during the third and final phase of local civic body polls in the northeastern Indian state of Assam, a senior police official said. "Clashes broke out after the tribals stabbed a security force personnel following which the police opened fire. All of those killed were tribals opposed to the state government's decision to hold panchayat elections in Goalpara district. Among those injured is a security force personnel deployed to ensure security in the local civic body polls," he said, on condition of anonymity. The injured have been admitted to a local hospital, the official said. Top police officials have rushed to the spot, he said, adding that a probe has been ordered into the incident.