A police officer was critically injured in a gun battle Saturday between Assam Police and their Meghalaya counterparts after the Assam personnel mistook the others for a group of militants, an official said.The incident took place in Moolaber, a bordering village between Meghalaya's West Jaintia Hills district and Assam's Karbi Anglong district, when both the police teams were raiding the area to flush out cadres of the Karbi Peoples' Liberation Tigers hiding there.Meghalaya Deputy Superintendent of Police Polster Syiem received a bullet injury. He was rushed to a hospital for treatment."Assam Police fired at our men (Meghalaya Police) thinking they were in a combat outfit. This forced our men to retaliate," Inspector General of Police in-charge Operations, G.H.P. Raju told IANS.