East Japan Railway says services on the Tohoku Shinkansen line have resumed after two linked trains became uncoupled. Operations between Tokyo and Shin-Aomori stations were suspended for about five hours on Thursday morning.

The operator says a coupler on the 17-car Tokyo-bound train became unhinged while it was between Furukawa and Sendai stations in Miyagi Prefecture shortly after 8:00 a.m. It says no cars derailed, but adds that this was the first incident of uncoupling on a moving train.

Takagi Ryo, professor at Kogakuin University, said it was natural to think that the device that detaches accidentally activated while the train was moving. This meant the two trains ended up apart.

The coupler connected the seven-car Komachi from Akita, with about 120 people on board, and the 10-car Hayabusa from Morioka, with about 200 on board. The operator says there were no injuries.

All the passengers remained on the train from the time of the incident until they were able to get off at Sendai station about five hours later.