A homicide investigation has been launched following the death of a baby in South Auckland.

A 10-month-old was taken from a Manurewa home to Starship children's hospital last night but died this morning, Detective Senior Sergeant Kevin Tiernan said.

"Police are speaking to a number of people in relation to the death," he said.

Police have now launched a homicide probe.

A scene examination was underway and a post-mortem examination was scheduled for Monday, Tiernan said.

"Police are in the very early stages of the investigation and are unable to comment further at this time," he said.

A St John spokesperson said two ambulances were called to a Williams Ave property in Manurewa at 5pm last night. One patient was transport in a critical condition to Middlemore Hospital.

Police were seen at a home on William Ave today.

A masked officer is standing guard outside the yellow two-storey house, where a police van sits opposite.

A second police car is parked on the concrete driveway of the house, with two other small cars parked outside.

The house overlooks Kirton Crescent Reserve, a small park with a playground including a slide and a swing set.

One neighbour told the Herald they hadn't heard of any disruption or issues until they saw a number of police cars arrive this afternoon.

Other neighbours declined to comment when approached.