Three labourers of General Reserve Engineer Force were killed on Monday after the terrorists attacked a GREF camp in Jammu district.
The attack took place in Battal area near the international border, police said.
"The attack has taken place in the morning. Reinforcements have been rushed to tackle the terrorists," a senior police officer said in Jammu.
The GREF is the parent cadre force of the Border Roads Organisation (BRO) that builds and maintains border roads in the country.