The Police Command in Edo State has named the suspects arrested over the Igueben train attack.
Gunmen on January 7 kidnapped passengers waiting to board the train to Warri in Delta State.
The Edo government had confirmed the arrest of two village chiefs and release of two remaining captives, both railway workers.
Police spokesperson, SP Chidi Nwabuzor said eight men already appeared in court where police got an ex-parte order.
The order obtained last week gives detectives a period of 14 days to continue with investigations.
The pleadings were signed by Barr. I. E. Ekibade on behalf of the State Criminal Investigation and Intelligence Department (SCIID).
In custody are Chief Ibadin Hamilton, 59, Halilu Umaru, 28, Aminu Ibrahim, 25, Friday Ighedujiemu, 51.
Others include Ighoko Mustapher Odion, 62, Okojie Dominic Ewa, 58, Ojie Patrick, 42, and Isah Aliyu, 25.
They allegedly conspired to abduct the victims and sought N20million from their relatives as ransom.
The offence is punishable under Section 2 (1) (2) of the Kidnapping Prohibition (Amendment) Law of Edo State.