The blast tore apart a three-foot section of track near Kokrajhar around 1 a.m., affecting several trains across Lower Assam and North Bengal.
Rail movement resumed after repairs and inspection; security has been tightened along the route.
CM Himanta Biswa Sarma said one suspect with prior cases in Assam and Jharkhand has been identified; probe underway to determine group links.
A suspected improvised explosive device (IED) blasted on the rail tracks in Kokrajhar district, disrupting the railway service across lower Assam and parts of north Bengal.
According to Himanta Biswa Sarma, the chief minister of Assam, police have named one person for their suspected participation.
Around five kilometres from the Kokrajhar railway station towards Salakati in the Alipurduar division of the Northeast Frontier Railway, the explosion occurred at one in the morning, according to an official.
"The blast ripped apart nearly three feet of railway line with fragments of the damaged track found strewn several metres away," he said.
Kokrajhar's Senior Superintendent of Police Pushpraj Singh said there were no reports of any casualties or derailment in the incident.
"The damage was limited to a short portion of the track, which was promptly repaired. Train movement has resumed now," he said.
Several trains in Lower Assam and northern West Bengal were affected by the nighttime suspension of railway services, which lasted until about eight in the morning, according to another official.
Before fully resuming operations, he said, railway and security staff thoroughly inspected the impacted area.
In order to find and capture those responsible, authorities have stepped up security along the route and opened an inquiry, he continued.
NFR's Chief Public Relations Officer Kapinjal Kishore Sharma said, "When a goods train was passing between Salakati and Kokrajhar, the train manager reported a heavy jerk, after which the train was stopped. On checking, it was found that there was damage on the track and sleepers due to a suspected bomb blast." State police, Railway Protection Force (RPF) and intelligence authorities are investigating the matter, Sharma said.
"The track was restored at 5.25 am and normal train services resumed. Around eight trains underwent detention due to the incident," he said.
He noted that patrolling in the area has increased after the event.
Speaking on the fringes of an official event in Bongaigaon, CM Sarma said that a loco pilot's prompt action saved the state from a perilous situation.
"When a train was passing, the loco pilot noticed it and immediately informed the railway police. If the loco pilot had not noticed and alerted us, we would have received very bad news today morning," he said.
Sarma said the police have identified one person allegedly involved in the incident.
"There are several cases registered against him in Assam and Jharkhand. Assam Police will be able to arrest him," he said.
When asked if any militant group is behind the blast, the CM said, "We have only got the identity of a person. Whether any organisation is behind him, it will come out only in the next phase of the investigation."
With PTI input.
