Emergency services remain at the scene of a house fire in Waltham.

A witness told Chris Lynch Media he called emergency services at about 7.20am after discovering a fire at an apparently abandoned house on Grenville Street.

“I was the first person there as far as I could tell and had already called 111 before anyone else arrived. The house was already fully engulfed, which was surprising given how early it was.

“The flames were spreading into nearby trees and bushes, and it looked like neighbouring homes could have been at risk.

“From what I personally saw, it appeared suspicious, but I obviously can’t say what caused it.”

Fire and Emergency New Zealand southern shift manager Angela Munro said the house was already well involved when crews arrived. Firefighters were continuing to extinguish the blaze.

Police have cordoned off the area, with Grenville Street partially blocked. The entire street may be closed while emergency services remain at the property.

The cause of the fire has not been confirmed.