Irish Rail has confirmed a woman got separated from her children this morning while boarding a train at Maynooth.
It is believed the woman jumped on the Sligo to Connolly train as the doors were closing, with the children still on the platform.
The woman subsequently pulled the emergency cord on-board and the train returned to the station.
However it is believed the train had not moved far.
A spokesman for Irish Rail said the driver did not see anyone else who appeared to be waiting to board the service on the platform.
He also explained that this was an Express service - meaning it would not be unusual for some passengers on the platform not to board.
Irish Rail say staff looked after the children for the few minutes the train was returning to Maynooth.