The A82 at Loch Lomond near Luss has been forced to close in both directions due to a crash.
Traffic Scotland alerted road users to the crash around 4pm this afternoon.
They have warned drivers to prepare for delays with congestion already heavy in the area.
Traffic information site INRIX report queueing traffic due to the accident from the Glen Luss turn off (Luss) to the A817 (Garlochead turn off, Shantron).
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Police confirmed that they were called to a two-vehicle crash and remain at the scene along with emergency services.
There are no details of any injuries.
A spokesperson for Police Scotland said: "We received a call at 3.20pm about a two-vehicle crash on the A82 at the junction for Luss.
"Emergency services are at the scene and the road is currently closed.”
