Christchurch residents leaving their homes as Port Hills fire spreads

A Christchurch couple have fled the raging fire engulfing homes in the Port Hills, saying "when you can see the flames, it's time to go".

About 1000 people have fled their homes as devastating bush fires threaten the city.

Niki Davis, a professor at the University of Canterbury, told the Herald just after midnight she had left her home on Bengal Dr in the suburb of Cashmere.

Earlier in the day she was standing at the end of her street staring at the "thick, black plumes" of smoke pouring from the hills.

However, as the fire encroached on her suburb she realised it was time leave.

"We could see the flames really right above us. When you see that it's time to go."

Her home wasn't officially evacuated by authorities but she said she left on her own will.

She said she would sleep in her campervan at her work carpark overnight.

Police and the Defence Force personnel have been going door-to-door evacuating residents in Cashmere Hills.

Davis said she could see fires burning in the Worsley Spur area, where two to three houses have been destroyed.

She earlier told the Herald the smoke was so heavy it shrouded parts of the fiery hills.

"You can't even see the hills in parts, the smoke is just so thick."

She said there was a strong wind blowing, which has hampered firefighters battling the huge blazes since Monday night.

Up to eight homes have been lost, with the fire claiming more than 1800ha of scrub.

A state of emergency has been declared and 120 firefighters, 15 helicopters and two aircraft have been battling the blazes.

One person, Ex-SAS serviceman and Waimakariri local David Steven Askin, died on Tuesday when his helicopter crashed while he was helping fight the fire.