Nagaon, Dec. 24: A low-intensity bomb went off on the rail tracks near Bokajan in Karbi Anglong last night, five minutes after the Dibrugarh-bound Rajdhani Express thundered past.

The bomb is suspected to have been planted by the Adivasi National Liberation Army (ANLA), purportedly to avenge the arrest of its “commander-in-chief” Nirmal Tirkey a few days ago in Jharkhand.

The site of the incident is just 9km from Chongajan, where the outfit had targeted the Rajdhani Express just over a year ago — on December 13, 2007 — killing five passengers.

Karbi Anglong additional superintendent of police (headquarters) Nityananda Goswami said though the damage to the track was minimal, the Rajdhani’s speed could have spelt disaster.

“The train was detained for a couple of minutes at Bokajan station. A railway team accompanied by GRPF personnel reached the spot and repaired the damage within an hour,” Goswami said.

The deputy inspector-general of police, Jiban Singh, visited the blast site this evening.

The bomb went off around 12.35am at Matipul just five minutes after the train had crossed Khatkhati station, Bokajan police said.

“It was a low-intensity timed explosive and that is why damage to the track was minimal. We found a small crater at the spot. A concrete sleeper had come off completely. In fact, the sound was not big enough for anyone to assume it was a bomb. It actually sounded like a tyre-burst. We realised what happened soon though, as railway officials rushed to the spot,” said David Ganju, a villager at Matipul.

Located between Khat-khati and Bokajan station, Matipul is an Adivasi-dominated village just 5km from Bokajan town.

Last night’s incident came just days after the Golaghat police took four hardcore ANLA activists into their custody from Jharkhand for interrogation in connection with various cases.

The four include the ANLA commander-in-chief and the mastermind of last year’s blasts Tirkey, spokesperson Prem Kawar, Dipen Nayan, alias Munna, and Arjun Orang.

The outfit was formed on September 20, 2004, at Nahartali of Merapani in the disputed “D” sector of Assam-Nagaland border with the ostensible aim of safeguarding the rights of the Adivasis.

It was formed under the leadership of the headman of Devidpur village, Arsen Ekka, and community leader Robin Lungao.

The activists received training from the Kuki Revolutionary Army on Singhasan hills in Karbi Anglong district in 2005 and began its operation in 2006.

It began by gunning down an ex-homeguard, Keshab Rana, of 2 Hirimbapur gaon under Merapani police station.

But its “coming-of-age” operation was in December last year when a bomb planted by the rebels tore through a coach of the Dibrugarh-Delhi Rajdhani Express, which continued to travel another 1.5km with bodies hanging out of the mangled steel and dropping off.

Overnight, the low-profile militants became the headline grabbing face of Adivasi insurgency.