Flames leap from the windows of a house in Waltham, Christchurch on Friday night.

A blaze which extensively damaged a Christchurch house on Friday evening is being treated as suspicious.

Both a fire investigator and police were on site at Walpole St in Waltham examining the fire-gutted villa on Saturday morning.

Specialist fire investigator Bruce Irvine said it was believed the fire was suspicious and was now a police investigation.

Joseph Johnson/Stuff Police and fire investigators were on site at a Walpole St house which was gutted by flames on Friday evening.

"Police are following investigative leads."

A police spokeswoman said police would go to the house to try and find out the reason behind the fire.

"Enquiries will be ongoing."

Joseph Johnson/Stuff A couple of locals watch on as police and fire investigators assess a Walpole St house that was gutted by flames early on Friday evening.

The fire started about 6.30pm on Friday night.

Three fire engines responded to "multiple calls" about the blaze, a Fire and Emergency New Zealand (FENZ) spokesman said.

Resident Scott Kale, who lives "two or three" houses down, was one of the first on the scene after he smelled smoke blowing towards his place.

SUPPLIED / KYM SMITH A house fire in Waltham on Friday night.

"It was pretty big, took hold pretty quick. It was sort of coming out the window a good couple of metres.

"It looks like the fire started towards the back of the house, in the kitchen area. Heaps of smoke, very thick. Quite a dark grey," he said.

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GEORGE HEARD/STUFF The Walpole St home was damaged along with a vehicle.

Some neighbours were there when Kale arrived, banging on the door to see if anyone was home, but no-one seemed to be.

Kale checked the neighbour's house because he was worried the fire would spread there.

Firefighters found the house well ablaze when they arrived.

GEORGE HEARD/STUFF Police, firefighters and paramedics attended the blaze.

"They immediately set about attacking the fire and, at this stage, there is no reports of any injuries or anyone inside the house, " the FENZ spokesman said.

He said the damage to the single-storey home would be "extensive".

The fire was under control by 7.50pm.

Kym Smith A house fire in the Christchurch suburb of Waltham on Friday night.

Earlier on Friday, firefighters doused an Ashburton house that was "well ablaze".