A 54-year-old man is said to be in a critical condition in hospital following an incident outside the Pen-y-Bont pub in Abergele.
Police say a man and woman, both local to the area, have been arrested.
Officers are now seeking witnesses to the incident, which is understood to have happened at around 10:30pm on Thursday.
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Wales have qualified for the Euro 2016 quarter finals after beating Northern Ireland 1-0 in Paris.
A rally has been held in Cardiff following the EU referendum to show support to migrant communities.
It's 0-0 at half time in Paris as Wales face Northern Ireland in the last 16 of Euro 2016.