The bus caused significant damage to the property in Wallace St, Mt Cook.

A bus driver has been injured and a resident stranded in an upper level of a house after a bus crashed into it in Wellington.

Emergency services were called to Wallace St, Mt Cook, just before 6pm.

The No 21 bus, which runs through Wellington from Karori to Vogeltown, crashed into the front of the house, damaging the entrance and the staircase.

SUPPLIED The damaged staircase after the crash.

The driver suffered minor injuries and was taken to Wellington Hospital by ambulance, police said. There were no passengers on the bus at the time.

The resident who was stranded was rescued by the fire service.

Power lines have come down on to the home, and appeared to be blocking the damaged staircase.

Sharne Jones, who lives two doors away, said she was sitting in her lounge when she heard a "super loud" bang.

Lisa Antonopoulous, who has owned the house for about 10 years with husband Andrew, was visibly upset as she surveyed the damage.

"The main thing is that everyone is OK, no-one was hurt, no-one was in the bus apart from the driver. God knows how the hell this happened."

MATT STEWART/STUFF Firefighters assess the damage after the crash. The driver, who was the only occupant, was taken to hospital with minor injuries.

Antonopoulous said structural engineers would survey the house tomorrow, and only then would she know if the residents would be able to move back in.

The house is divided into two flats, with three people living in the apartment downstairs and three upstairs.

Go Wellington bus company offered to put up the residents overnight.

LUCY SWINNEN/STUFF One resident of the house was briefly trapped upstairs, before being rescued by firefighters.

One said they were concerned about where they would live until the house was repaired, which could take some time.

It is likely a structural engineer will be called in to assess the house before the tenants are allowed back in.

Police said the northbound lane would remain blocked as police tried to remove the bus with heavy machinery.

LUCY SWINNEN/STUFF Police and ambulance crews attend the scene in Wallace St on Thursday evening.

The accident happened at the southern end of Wallace St, at the intersection with John and Hutchinson streets.

NZ Bus southern chief operating officer Tonia Haskell said it was unclear what caused the accident.

The police serious crash unit was investigating, and the bus would be taken to the company's Wellington depot for a full inspection, she said.

"We don't know what happened. For now, it's just making sure the bus is all right, and the driver's all right."