A Westpac rescue helicopter was called to an Upper Hutt tavern after a person was found unconscious on Tuesday afternoon.
Police were called to reports of an unconscious person outside the Rimutaka Tavern on Fergusson Drive at around 4:40pm.
Two ambulances, eight police cars and one rescue helicopter were called to the scene.
One person is in a serious condition and was transported to hospital, police say.
"At this stage, it is not clear what has happened."