At least six persons, including a sub-divisional police officer and three policemen, were seriously injured in an ambush by ULFA militants in Upper Assam's Sibsagar district on Tuesday.
The police said the sub-divisional police officer Jayanta Sarathi Bora and his team were travelling near the Khona Tea Estate when they discovered an object near the bridge.
On approaching the object which looked like a box, it exploded as a result of which Bora and three policmen were injured.
Two other civilians who were nearby were also injured.
They have been admitted to the Assam Medical College Hospital at Dibrugarh.
A massive hunt have been launched to nab the ultra who managed to escape.