In this photo taken on Feb 1, 2023, residents wade through a flooded street after torrential rain at the suburb of Langholm in Auckland. (PHOTO / AFP)

WELLINGTON — The worst of the forecast rain moved away from New Zealand's flood-ravaged biggest city on Wednesday after inflicting what the finance minister described as probably the "biggest non-earthquake event" in the country's history.

Four people were killed in flash floods and landslides that hit Auckland beginning on Friday as rainfall, that authorities say has been exacerbated at least in part by climate change, drenched the city.

Rain over the 24 hours to early Wednesday caused more surface flooding in the city of 1.6 million people and forced the closure of several roads and rail lines

"Our job is to look after people, help people recover," Finance Minister Grant Roberston told media.

READ MORE: New Zealand roiled by flash floods, landslides for third day

He said the flooding was probably the most significant disaster apart from earthquakes that New Zealand had ever had to deal with in terms of insurance.

A state of emergency remains in place in Auckland but has been lifted in the Northland region to the north of the city.

Rain over the 24 hours to early Wednesday caused more surface flooding in the city of 1.6 million people and forced the closure of several roads and rail lines.

Sodden ground was causing risks particularly from landslides. A house collapsed down a cliff injuring three people in a beach settlement near Auckland on Wednesday.

The national meteorological service said the heaviest rains had passed Auckland although downpours were hitting to the southeast, in the regions of Coromandel and Bay of Plenty.

Rachel Kelleher, Auckland emergency management deputy controller, said the likelihood of more flooding was lower but the water-logged ground meant danger from landslides and falling trees.

"This has been an unprecedented event," she said.

READ MORE: NZ counts cost of Auckland floods, more rain forecast

People in the city of 1.6 million are being asked to stay out of the sea and flood waters because of fears of contamination but all Auckland schools, which had been told to close until Feb 7, can now open if they have not been impacted by flooding.

Evacuation centres remain open across the city.

Summers in New Zealand usually bring some rain but the region is experiencing the La Nina weather system, which can bring much heavier rain to the upper North Island.