UPDATED 5.33PM: A 24-year-old man is dead and his cousin in hospital, after a fight at a 21st birthday party in Auckland.

Police were called to Fisher Crescent in Otara around 1 this morning, where they found Chevy Davis dead on a driveway.

Mr Davis' 28-year-old cousin was badly injured inside the house.

He was taken to Middlemore Hospital, where his injuries have improved and are no longer life-threatening.

Detective Senior Sergeant Ross Ellwood says police were called to the house after the fight.

"There's been an altercation that's taken place around one a.m., or shortly before one a.m. this morning, which has led to a young man being badly injured and another young man being killed at that address," he says.

Police are at the house today to piece together what happened.

Police are confident they'll make an arrest today, and want to hear from anyone with information that might help them.

Detective Senior Sergeant Ellwood says they'd like to hear from anyone who has any information about last night's events.

"We're following a number of strong lines of inquiry and we certainly hope to have a result in the next 24 hours in terms of an arrest in relation to this event."