Agartala, Feb. 14: Tribal militants killed an engineer and two labourers in an ambush on a survey team of the Gas Authority of India Ltd in Tripura today, bringing the ongoing exploration project in the Atharomura hills under a cloud.

The National Liberation Front of Tripura targeted the survey team at Badhaniapara, in the interiors of Atharomura, around 8.30 am. Police said the rebels were perched on the edge of a hill, from where they hurled two grenades.

Engineer Sujan Saha, 32, and labourer Haradhan Malakar, 42, died on the spot. Gopal Sarkar, 30, died in a second attack minutes later.

A unit of the Tripura State Rifles (TSR) had escorted the survey team, including technical personnel and labourers, from Agartala to Tuipuimura in West Tripura district on a mini truck.

From there, the security personnel and the survey squad proceeded to Badhaniapara ? south of the Assam-Agartala highway ? on foot. The team had barely started work after the two-km trek through jungle terrain when the militants struck.

The TSR personnel retaliated immediately, but the militants escaped unscathed. As the security contingent ran towards the highway with an injured Gopal Sarkar, the militants launched another attack. A bullet struck the already injured worker and he died on the spot, the police said.

The ambush was the first major militant attack this year and came just 13 days before the first phase of elections to the 527 village committees under the Autonomous District Council.

A security contingent, led by superintendent of police (west) Rajesh Kambley and TSR commandant L. Darlong, rushed to the spot and have begun a combing operation.