Police are out in force in Wellington this morning after yesterday's massive operation to clear the illegal occupation off Parliament grounds.

There were chaotic scenes as protesters scrambled to save what gear they could and some were pepper-sprayed.

People set fire to trees and tents and loud bangs could be heard - possibly gas canisters exploding - as the flames spread - damaging the children's playground and surrounding trees.

The fires were put out, allowing police to push protesters onto the streets but tensions simmered for hours.

At the height of the confrontation officers fired sponge bullets and protesters hurled bricks, pieces of of wood, rubbish and traffic cones in running battles on central city streets.

When they ran out of things to throw, they started digging up bricks from the footpath on Lambton Quay.

A high-powered water hose was also used by protesters showering police with paint petrol and water.

As of late last night, 87 people had been arrested for offences including trespass, wilful damage and possession of restricted weapons.

Police Commissioner Andrew Coster this morning said they would investigating footage of yesterday's unrest and further arrests would be made.

He said seven police officers remained in hospital overnight, but none had life-threatening injuries.

Yesterday, Prime Minister Jacinda Ardern said the violence was deeply saddening.

Follow RNZ's coverage of the protest at Parliament here: