Two helicopters landed on Auckland Domain tonight and an ambulance was spotted picking up something from one aircraft.

One bystander said an ambulance crew met one of the helicopters after it landed on the main Auckland Domain cricket field, near the historic wooden grandstand.

She said a gurney was taken to and from the helicopter but it did not appear there was anyone - or anything - on it.

The second helicopter swooped around the Domain.

"It was so low on its first cross that our house shook," said one resident.

Another bewildered resident said he saw the helicopters land on the Domain around 8pm before they took off around 10 to 15 minutes later.

A spokesman for Auckland Westpac Rescue Helicopter said they were not involved.

Meanwhile, a police spokeswoman said she was unaware of any incidents involving helicopters landing on the Domain.