Three men were arrested by armed gardai following reports of a firearm on board a DART in North Dublin.
Officers rushed to Harmonstown Station at around 1.20pm on Friday where they intercepted the southbound train and arrested the men.
A silver pellet gun is believed to have been found at the scene, while it is also reported that three individuals were "engaging in drug use".
A garda spokesman told Dublin Live the men were taken to Clontarf Garda Station while the investigation is ongoing.
He said: "Gardai are investigating a public order incident that occurred on a DART at approximately 1.20pm on Friday 13th September 2019.
"Gardaí intercepted the DART at Harmonstown and three males were arrested.
"They are currently being detained under Section 4 of the Criminal Justice Act 1984 at Clontarf Garda Station. Investigations are ongoing."
Irish Rail Spokesperson Barry Kenny confirmed an incident and said there was also a report that drugs were being used on the train.
He told Dublin Live: "Gardai attended after a report of three individuals engaged in drug use on board.
"They have since taken them from train."
The incident resulted in thirty minute delays across the southbound line while other services also had to be put back.
It came just hours before 50 gardai were present across Luas, DART, and commuter trains as part of a new operation.
Today was the first day of the new initiative designed to "support transport operators in ensuring a safe and secure travelling environment for customers".
Members of the force travelled on public transport from 3pm until the end of services on Friday night.
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