The A55 will be closed for a "considerable amount of time" following a "serious" crash, police said.
The incident happened eastbound at Penmaenbach Tunnel, Conwy, between junction 16 and junction 17 this morning, according to traffic analysts Inrix.
North Wales Police said the eastbound carriageway "will be closed for a considerable amount of time".
The force has added that eastbound traffic is being diverted off at J11 (Llandegai) onto the A5."
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