Sirajganj Government Railway Police (GRP) has detained four rail employees in connection with the derailment of Rangpur Express in Ullapara upazila of Sirajganj district.
They were detained early Friday.
However, GRP still has not taken any action against the station master, who was in charge, or the loco master of the train.
Among the detained, three are track labourer Ariful Islam, mechanics Abdur Razzak and Mokbul Hossain. The identity of the other detained could not be verified.
Sirajganj GRP station Officer-in-Charge Harun Majumder said: "They are being interrogated, not jailed."
Pakshi Western Rail Division Divisional Traffic Officer (DTO) Md Abdullah Al Mamun made a similar comment.
On Thursday, the engine and seven bogies of Rangpur Express derailed after the train, bound for Rangpur, left the Ullapara rail station. The engine along with four bogies caught fire.
Around 25 people were injured in the incident. Three probe teams have been formed to investigate into the matter.
After the accident, rail links between Dhaka and the northern districts remained cut for nearly seven hours, collapsing the schedule of trains of that route.
