A competitor in the Motatapu Allpress Espresso Trail Marathon has been flown to hospital after suffering a medical emergency.
Race director Gemma Peskett said Hato Hone St John and the event organisers were notified at 11am of the incident.
A Hato Hone St John spokesperson said two ambulances and one helicopter responded.
One patient in a critical condition was treated at the scene and airlifted to Christchurch Hospital, they said.
The Allpress Espresso Trail Marathon begins at Motatapu Station, Wānaka, and ends at Wilcox Green in Arrowtown.
