Strong winds have blown two trucks into structures on the Auckland Harbour Bridge and caused traffic havoc, now stretching for kilometres.
The crashes have closed two northbound lanes as emergency services work to clear the wreckage and traffic is backed up on either side.
NZTA Auckland system manager Andrea Williamson said that just after 11am the wind was gusting at just over 60km/h, but suddenly picked up to blow for several minutes at up to 127km/h.
"A medium-sized truck travelling in lane 3 northbound was hit by a strong gust of wind and blown across two lanes. It toppled over the moveable lane barrier and is now stuck on the barrier. The driver was not injured."
The truck was from courier company Castles Parcles.
"At the same time a southbound truck carrying a shipping container was blown sideways and hit the bridge superstructure," Williamson said.
"The truck righted itself and carried on.
"There is damage to the bridge overarch, with a steel upright sheared off.
"The four lanes in the bridge centre span will remain closed until the damaged upright is assessed and repaired."
The clip on lanes north and south remained open, but there was heavy congestion with traffic backing up.
NZTA said that to enable safe recovery of the truck all northbound lanes will temporarily close for up to 30 minutes from about 12.50pm.
"Please delay your journey north or consider using SH16/18 as an alternative."
By 1pm, two of the northbound lanes had reopened.
A St John Ambulance spokesperson said one person was being taken to North Shore Hospital in a moderate condition.
Police said they received a report of a truck tipping over just after 11am.
"There are no reports of serious injuries at this stage, however a number of lanes in the centre of the bridge are currently blocked. This is impacting traffic heading north and south.
"Police are on scene along with other emergency services who will work to clear the scene.
"Motorists are advised to expect delays in that area and to drive to the conditions this afternoon."
St John was alerted at 11.10am. One ambulance and two managers tended to the injured person.
NZTA also warned motorists to avoid travelling across this section of motorway following the dramatic accident.
"The two clip-on lanes remain free-flowing but very slow heading north over the bridge."
Recovery of the wreckage is expected to take several hours.