Iarnród Éireann has apologised to passengers who travelled on the early-morning Killarney to Dublin train yesterday after they had to break into the station to board the 6am train.
More than a dozen people had arrived at the station, which serves south Kerry and the tourist town, to find the gates and the ticket office locked.
When the train from Tralee pulled up at the platform, a guard got off and, with the assistance of a crowbar and at least one passenger, managed to prise open a lock on the side gate so that passengers could make their way through to the platform.
The passengers were able to buy their tickets on the train after they had boarded.
The train, one of the modern commuter trains linking Killarney with the early-morning Dublin train from Mallow, left the station about 10 minutes late.
Passenger Michael Fortune from Killorglin said: "I would not have believed it myself only I was there."
Mr Fortune said that he had helped the guard to prise open the lock on the side gate with the crowbar. He added that he hoped he was not going to be accused of causing criminal damage.
Mr Fortune said he felt that passenger safety might have been compromised: "It's not good enough. They should have had back-up."
Iarnród Éireann yesterday issued an apology to passengers but insisted that safety had not been compromised. The company said that there had been a mix-up or some confusion over staff rotas.
It had been a highly unusual event at such a well-run station, spokesman Barry Kenny said.
The Killarney station, which has recently been allocated extra services to Dublin, Tralee and Cork, is one of the State's best-kept stations and regularly features among the prizewinners in the national Tidy Towns competition as well as in local and regional competitions.
It has also featured in period films, including The Wind That Shakes The Barley.
Last month it won third prize in the inter-city category in this year's best railway station awards, which were presented by Minister for Transport Martin Cullen.
It has also won prizes for its floral displays.