A person has died after falling from a neighbouring building on to Newmarket train tracks this afternoon.
A police spokesman said officers arrived about 12.15pm and were still examining the scene of the fatality.
It appeared the deceased person had fallen off a neighbouring building and landed on the tracks, the spokesman said.
All train lines in and out of Newmarket were currently closed as a result.
A St John spokeswoman said two vehicles attended the incident about 12.15pm.
One patient with critical injuries was treated but no transport was required.
No further details could be released, she said.
A Fire Service spokesman said a unit had attended.
Auckland Transport said a train shuttle was operating between Onehunga and Penrose.
Passengers travelling to stations on the Southern Line between Otahuhu and Newmarket should use scheduled buses from Great South Rd, it said.
The delays come on the first day of the electric train roll-out, with Auckland Transport replacing its remaining old diesel trains with electric trains on all lines from Papakura and Swanson to Britomart today.