The train line between Troon and Ayr has closed this evening.
ScotRail have tweeted moments ago that due to a problem, the line has been shut down.
Now train services between Glasgow Central and Ayr will be cancelled, delayed or revised while the issue is investigated, bosses have stated.
The transport blow comes as thousands have flocked to the Ayrshire coast for a day in the sunshine during the Queen's Platinum Jubilee celebrations.
ScotRail tweeted: "Due to a problem currently under investigation between Troon and Ayr the line is closed. Train services between Glasgow Central and Ayr will be cancelled, delayed or revised."
The news is the latest in a series of body blows to the region's transport infrastructure.
Yesterday, ScotRail implemented huge changes to Sunday services in Ayrshire.
Crunch talks are still ongoing between bosses and drivers' union ASLEF after the union rejected a pay offer put forward by the Scottish Government owned rail operator.
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