Acting on a tip-off, a team led by Superintendent of Police Nitul Gogoi, launched an operation in Bogolamari area of Dudhnoi police station last night to rescue Meghalaya Sericulture Officer Dilip Dutta Medhi.
Medhi was kidnapped on November 14 along the Assam-Meghalaya border.
The militants ambushed the police team and an encounter followed in which four militants were killed and two managed to escape while the kidnapped official was rescued, police said.
Combing operations were continuing in the area and the rescued official was brought to Dudhnoi for medical treatment, they said.
Medhi was kidnapped on November 14 along the Assam-Meghalaya border while he was on his way to Guwahati from the neighbouring state, sources added.