A construction worker is in a critical condition after scaffolding he was installing on units in an Auckland suburb collapsed, trapping him underneath.

A St John Ambulance spokesperson said two ambulances and two rapid-response vehicles attended the accident on Dunbar Rd, Mt Eden, at 8.26am.

"We treated and then transported one patient in a critical condition and one in a minor condition to Auckland City Hospital."

A Fire and Emergency spokesperson said firefighters helped rescue the trapped worker.

A police spokesperson said emergency services were in attendance at the workplace incident in Mt Eden.

"One person has sustained serious injuries and has been taken to hospital," the police spokesperson said.

"Enquiries are ongoing and WorkSafe has been notified."

WorkSafe has been approached for a comment.