GUWAHATI - A massive military operation was launched Monday after tribal separatists gunned down 11 people and wounded 15 in an Assam village, officials said.

The incident took place late Sunday when heavily armed militants of the outlawed National Democratic Front of Bodoland (NDFB) attacked Bhimajuli village in Sonitpur district, about 240 km north of Guwahati, a police spokesperson said.

A group of about eight to 10 NDFB militants using automatic weapons opened indiscriminate fire on villagers killing 11 people on the spot. Four women and several children were among those killed.

“The situation is tense with army soldiers accompanied by police commandos and paramilitary troopers conducting an operation in the area to track down the militants,” Assam Fishery Minister Nurzamal Sarkar told IANS.

Sarkar is the local legislator from the area.

“Of the 15 injured, at least four of them are said to be critical,” the minister said.

On Monday, angry villagers armed with bows and arrows, machetes and spears, roamed the streets along side security forces.

“Inordinate delay by the police to reach the site of the massacre led to a number of people succumbing to their injuries. The militants were at our village for close to an hour and despite the police being informed of the attack, they failed to arrive on time,” Subhas Chetri, one of the first to have informed the police, said.

Chetri suffered bullet injuries on his legs.

“The NDFB probably attacked the village after the locals there refused to pay extortion money. The militants had served extortion demands to locals in the area,” the minister said.

The NDFB is a rebel group fighting for an independent homeland for the Bodo tribe in Assam .

A faction of the NDFB is operating a ceasefire with New Delhi, although another group led by guerrilla leader D.R. Nabla is still underground.

The NDFB is blamed for the Oct 30 serial blasts in Assam that killed about 100 people.

More than 10,000 people have lost their lives to insurgency in Assam during the past two decades.