A Hamilton accountant has appeared in court over charges relating to driving off the top of the Wilson Parking building in Alexandra Street.

The car that plunged 10 metres off the top of a Hamilton car-park building had been doing donuts in the space, a witness says.

The two occupants of the car, a man and a woman, survived the crash, though the man was said to have suffered serious injuries. Both were in a stable condition in Waikato Hospital on Friday. Emergency services were called to the scene just before midnight on Thursday.

The witness, a resident of a Victoria Street apartment building, was out on her seventh-floor balcony and heard "hooning, revving noises" and looked over to see the car on the third level of the Alexandra Street Wilson Parking building.

CHRISTEL YARDLEY/FAIRFAX NZ The missing guard rail shows where the car plunged off the car parking building.

"They were going round and round in that open space where there's nothing built on. They were wild and it looked like they were doing all that racket for fun," the woman said.

The car parked up briefly for a few minutes before the crash, the woman said, and she saw at least two other people standing near it.

The sedan then sped off as if to start doing donuts again, but made a turn towards Alexandra Street "and hit the accelerator as hard as they could".

CHRISTEL YARDLEY/FAIRFAX NZ The point where a car reversed off the parking building.

"I remember seeing what looked like headlights to me coming towards the safety barrier, not reversing lights," she said.

"My panic grew as I waited to see any sign of red lights coming on, as in brake lights, but it never happened."

It looked as if the driver was trying to "fly off the car park", she said.

PHOTO/SUPPLIED Police stand guard at the scene where the car plunged off the third floor of the Wilson car park building.

The noise was enough to make her husband run out on to the balcony to see what was happening.

The woman believes the car was going forward when it smashed through the safety barrier, and may have spun when the front got caught in the glass awning of a Alexandra Street shop. It landed on its wheels.

Another witness, cleaning contractor Ricky Ngaronga, thought the car left the third floor in reverse.

CHRISTEL YARDLEY/FAIRFAX NZ The view from the third floor, through smashed glass panes, to the footpath below.

"It landed on the glass panes [on the way down], then went a**-up [before] landing on its wheels," he said.

"I'm surprised they survived. There was just s*** all over the road, glass everywhere on the footpath."

Ngaronga said there was a man and woman in the silver sedan who looked to be in their late 20s to early 30s.

"Those fellas obviously thought they had wings, eh?" he said.

"The car is done, eh. Smashed, front and back."

He said two rail guards and chunks of concrete landed on top of the car.

"We see lots of stuff like this. We started work at 10pm last night - we're the night crawlers. When you wake up in the morning and the streets are all clean and beautiful? That's us. So this isn't anything new."

Hamilton Police Senior Sergeant Damion Rangitutia said police were still investigating and tests are under way to confirm whether alcohol or drugs were a factor.

A Wilson Parking spokesperson said the company is working with the Waikato Serious Crash Unit, which is investigating.

"As with any incident of this nature, Wilson Parking will conduct a full review," the spokesperson said.

"There are wheel stops in place in front of the barriers, but it appears that the vehicle was travelling at speed and as a result, it jumped the wheel stop and breached the barrier.

"An initial review of the site this morning found the perimeter barriers on level three of the car park where the incident took place to be compliant and the rest of the property safe.

"The affected area is cordoned off while investigations and repair work is completed."

A WorkSafe spokesperson said on Friday it had not yet been informed of the incident.