THE A467 is closed in both directions near Pantside and Newbridge after debris fell onto the road.
Emergency services are on the scene but Gwent Police are asking people to stay clear of the area.
No one has been hurt.
Diversions are in place, and this is causing congestion.
Large queues of traffic are still in the immediate area.
A Gwent Police spokeswoman said:"We received a report of debris falling on the carriageway of the A467 between Pantside and Newbridge shortly before 2.40pm today.
"Damage was caused to a windscreen of a vehicle.
"No injuries reported to the driver of the vehicle.
"Both sides of the A467 from Pantside to Newbridge are currently closed."
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