The two militants who went on a motorcycle to a construction site of a PWD bridge at Kumuria village opened fire on the labourers, the sources said.
Two labourers Rafique Ali and Safiur Khan were injured seriously and admitted to Barpeta Medical College and Hospital, they said.
A month earlier, two youths who identified themselves as NDFB(S) cadres had come to the construction site and taken the mobile number of the owner of the bridge construction company, they said quoting the labourers.