Smoke is billowing from the scene of a vehicle fire on the Fishguard to St Davids road.
Originally it was thought that there had been a collision between a car and camper van near Crug Glas.
A spokesman for the fire service said the incident was a vehicle fire involving a motorhome towing another vehicle.
No other vehicle is believed to be involved.
Fire crews from Fishguard and St Davids are currently at the scene, as are police who are diverting traffic.
Dyfed-Powys Police said they received a call reporting that a car and campervan had caught fire on the A487 St David’s to Mathry road at just after 11.30am.
"The road is blocked and officers are diverting traffic which has built up," said a police spokesman.
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