Fire-proof walls helped contain a major blaze in an apartment unit in Christchurch, Fire and Emergency says.
One person has been taken to hospital in serious condition after Tuesday night's fire in a two-storey apartment on New Brighton Road in the suburb of Shirley.
Two other people were injured in the fire that was "well ablaze" when fire crews arrived.
Southern shift manager Simon Lyford told Morning Report the fire doors in the building stopped the flames spreading beyond one apartment.
"It appears the damage was contained to the one apartment, so the fire walls etcetera have worked extremely well and contained the fire to the one apartment.
"It does sound like it's extensively damaged."
Lyford said four crews left the scene just prior to midnight but a fire investigator would be at the complex to investigate its cause.
He had no knowledge as yet of what may have started the fire.
Jerico Tana lives in the neighbouring apartment and said he and his partner heard people screaming, and saw white smoke.
"We really got scared then just ran and then everything happened so quickly, and there's a lot of people.
"We heard more explosions and we saw the people outside there also jumping from the second floor because I think there's two children sleeping when it happened."
Christchurch East MP Reuben Davidson said he will be visiting residents from the apartment block.
He said residents were concerned for the safety of those in the complex - and local councillors will be visiting community members this morning.
"I believe this is a new apartment complex, quite close to The Palms Shopping Centre, so it's a busy community and I'm sure there's a lot of concerned neighbours and concerned residents who are worried that those who live there are all okay."