All the seven hailed from different parts of UP and various cases had been filed against them in Tamil Nadu and Andhra Pradesh, a GRP release said.
"The investigation reveals that they were part of a gang involved in the train robberies and their commission of offence involves stopping the train by pulling emergency chain and (the gang) numbering around four to eight will snatch the chains of passengers lying in berths close to the windows," it said.
Efforts are on to arrest a few more absconding accused and to recover the properties robbed, including 100 sovereign gold ornaments, it said.
The accused were nabbed by special team headed by deputy Superintendent of Police (DSP) V Ponram, it added.