Hundreds of commuters were evacuated from a busy train as a fire safety precaution.
ScotRail have confirmed an oil leak fell onto a hot exhaust, with the resulting smoke triggering the onboard fire prevention system.
The six carriage service, was full to the brim with passengers heading for Glasgow from Edinburgh at around 4pm last Friday.
One passenger, said: “Someone said they saw smoke coming from the engine, but I’m no sure. All I know is we were evacuated from the train in a hurry.”
The incident caused some disruption, with hundreds left stranded on the platform at Lenzie station.
A ScotRail spokesman said: “We would like to apologise to customers for the delay caused by this incident.”