Was it the locomotive that the people got into? Or the other thing at the front.
I've often seen doors open on loco's leaving connolly.
According to this mornings metro there was people standing on the track which was why the train stopped. Apparently it was a group of scouts who had there luggage taken on the train.
Personally, bar the usual lack of info and customer service, I would be fairly slow to attach blame to the rail companies for this one. It sounds like a fairly crazy occurance, not something you would expect to happen.
