The Fire Service has apologised to the families of victims unable to be rescued from the collapsed Canterbury Television building.

The final week of a coroner's inquest today heard evidence into the deaths of eight victims who were known to have been alive after the building collapsed in the February 2011 earthquake.

Fire Service operations and training director Paul McGill began his evidence with a apology to families.

''That was a dreadful situation and we're sorry for what occurred there,'' he said.

Nigel Hampton, representing Alec Cvetanov, whose wife Tamara died in the building, said his client was ''touched'' by McGill's sincerity.

Cvetanov had long felt he was a ''lone voice'', Hampton said.

An Urban Search and Rescue technician earlier told the inquest he was in disbelief at hearing signs of life from within the collapsed Canterbury Television building rubble.

Chris Kennedy, a Usar technician who worked on the eastern, or Madras St, side from about midnight said he and colleague Ian Penn heard "banging" after they tapped on a concrete slab three times.

He was shocked given the pancaked state of the building.

''I couldn't believe it at first, then we heard bangs back at us - someone had answered us. When I looked at Ian again there was disbelief in his face.

''I said to him, 'I heard that', and he said, 'Same'. We did it again and then we waited. There was another tap."

The pair kept the find quiet until it could be confirmed.

''We banged again and we got another reply. Straight away we were like, 'Yip, we've found somebody'."

The crew began cutting a hole nearest to where the sound had come from using crowbars, sledgehammers and breakers instead of power tools.

The method was "quick and effective", Kennedy said.

''I remember we only had limited tools and didn't have all our equipment on the ground with us as it was still being driven down,''he said.

The rubble was "packed tight" and cutting through was "painstaking".

Impeding progress was crushed chairs, desks, cabinets and ventilation ducts.

"Everything you see inside a building was compacted down to 300 millimetres," Kennedy said.

He spoke three times to Alec Cvetanov, whose wife, Tamara Cvetanova, was trapped and communicating by phone from inside the rubble, but could not guarantee she was the person tapping.

Rescue crews were pulled out of the hole when a fire at the sign became "raging" and the smoke unmanageable, even with respirators.

Machinery was used to remove rubble, which uncovered several bodies, but no voids were found.

Cvetanova was not found alive.

Kennedy felt his team was on the back foot because its full cache of tools had not arrived, but did "everything we could with the resources we had at the time".

He later saw the remains of the collapsed Pyne Gould Corporation building, which "still looked like a building", and noted the obvious voids and entry points for rescue.

In comparison, CTV looked like a "pack of cards had been dropped", Kennedy said.

Usar technician Ian Penn earlier rejected suggestions a hole dug to locate CTV building collapse survivors was delayed more than five hours.

Penn said work on a hole began shortly after his team arrived about midnight or 1am.

The spot chosen was nearest to where knocking had been heard from within the rubble.

Photographic evidence suggested the hole was started much later, after gear arrived by truck about 5.30am.

Penn defended his recall of the time when quizzed by counsel assisting the coroner Richard Raymond.

"Are you stating we'd literally done nothing for four to five hours?"

Penn said his team had "limited kit", but said it did not hamper entry into the rubble.

"We did have limited kit, but it allowed us to do the job we needed to do."

Hand tools, such as sledgehammers and breakers, were used.

The North Island-based team's power tools did not arrive by truck until the morning of February 23.

Raymond said other Usar members had given evidence that the availability of hand tools slowed progress at the site.

"I don't disagree with that, but I don't think it hampered our performance on the job," Penn said.

Listening equipment was sought, but was not available, he said.

The inquest is being streamed live on the Justice Ministry's coronial services unit website.

- © Fairfax NZ News