Government Railway Police (GRP) of Akhaura yesterday picked up seven people for interrogation in connection with the killing and robbery at Titash Commuter Train.
Three passengers were killed and another was injured when a gang of muggers pushed them off the Dhaka-bound running train in Brahmanbaria Sadar upazila early Thursday.
Abul Kalam Azad, officer-in-charge of Akhaura GRP Thana, yesterday said they picked up most of the suspects from Brahmanbaria district.
He, however, declined to divulge their identities for the sake of investigation.
"After interrogating them, we will find out the real culprits and show them as arrested," said Azad, also the investigation officer of the case filed in connection with the incident.
Railway sources said two railway staffs were killed after some criminals threw them out of a running train on Dhaka-Chittagong route in 2008.
In another incident in March 12, 2008, five robbers hacked Md Samsul Haque, attendant of a Dhaka-bound mail train from Chittagong, to death and dumped his body in the toilet of a carriage.
The murder was committed before the train reached the Akhaura railway junction in Brahmanbaria.
JC Mandal, a guard of Turna Nishitha Express, was killed by some muggers near the junction, four months before the killing of the train attendant.