Paisley town centre was evacuated after reports of a suspected gas leak which is now believed to have been a smell caused by a stink bomb.
Emergency services were called to JD Wetherspoons’ The Last Post pub at about 21:10 on Sunday.
Fire appliances, ambulance and police attended after customers complained of feeling unwell.
Several people were treated as a precaution.
ScotRail cancelled its Glasgow Central to Ayr service for a short time due to “emergency services dealing with an incident near the railway”.
A cordon was extended to the surrounding streets and social media reports suggested up to eight fire appliances were in attendance along with police and ambulance teams.
Eddie Gorshon, spokesman for JD Wetherspoon, told the BBC Scotland: “At around 20:15 the pub manager was alerted to a gas substance in the air by a staff member.
“The gas engineer arrived and he concluded that it was not a gas leak. The manager was told to keep everyone out of the building.
“At around 21.30 the fire brigade and police arrived and begin to set up a cordon around the entire pub and shut Paisley Gilmour street train station.”
Mr Gershon said the incident is believed to have been triggered by the letting off of a “stink bomb”.