Three security personnel were killed and two others injured on Wednesday night when Naxalites blasted a police outpost building at Vishrampuri in Bastar district of Chhattisgarh.

Cadres of Peoples Liberation Guerrilla Army, the military wing of the outlawed Communist Party of India-Maoist, triggered a blast targeting the police outpost at Vishrampuri at about 2000 hours, police sources said.

The number of security personnel present inside the police outpost was not confirmed, but the possibility of more casualties were not ruled out, senior police officials said.

"The police outpost is still engulfed in fire," sources said, adding that additional security forces from district headquarters Jagdalpur and nearby Kanker district have been rushed to the spot.

However, security personnel were heading to the spot cautiously in view of the possibility of Maoists laying landmines on their way to Vishrampuri.

Maoists had stepped up violence in tribal Bastar region during the last three years, particularly after the local tribals launched Salwa Judum -- an anti-Naxalite movement -- in June 2005.

The rebels retaliated with attacks against those participating in the movement and unleashing violence against security personnel, including paramilitary forces.

According to official figures, more than 800 people, including security personnel, were killed during the last three years in Bastar where the Maoist rebels and security personnel were engaged in an armed conflict.