A 34-year-old man has been arrested at Harpenden train station on suspicion of possessing an offensive weapon.
British Transport Police were called at 2.22pm to the station following reports a man was causing a disturbance.
It is believed he was having a verbal altercation with another passenger.
Officers arrested the man on suspicion of possession of the weapon, criminal damage and a public order offence.
It is not know what sort of weapon it was.
Witnesses reported police officers armed with tasers arresting someone at around that time.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here