An injured man in critical condition was found unconscious in the Auckland Domain overnight.
Police say the man was found at 12.45am and it is unknown how he received his injuries.
The area around the Wintergarden Pavilion, including the cafe's outside dining area, has been cordoned off by police, and is guarded by a police car.
The main road through the Domain, from the Grafton entrance at Auckland City Hospital, is also cordoned off. However, access to the pitches and the museum is open.
Early morning walkers and runners are still using the park, despite the rain and crime scene nearby.
A blue crime scene tent has been erected on Domain Drive on the road alongside the duck ponds.
It is cordoned off at either end, with a police guard on both sides. Officers are turning away runners and people walking their dogs.
