A vehicle towing a trailer that stopped part way across Ngaruroro Bridge is believed to have been the catalyst in an "unusual" four car pile-up, which saw one woman taken to hospital.
Police Constable Mark Brinsdon understood the vehicle halted to "tie something on to the trailer" shortly before the crash, about 1pm yesterday.
He said a car following it stopped, while a "distracted" driver in a third vehicle hit the second in line, forcing it into the opposite lane, where it was struck by an oncoming vehicle heading north towards Napier.
"A four car pile-up is unusual," Mr Brinsdon said.
"All drivers were okay, bar one female."
The woman was transported to Hawke's Bay Hospital, where a spokeswoman said she was listed as being in a stable condition late yesterday.
St John Ambulance Hawke's Bay territory manager Brendon Hutchinson said the patient, in her late 30s, was treated for a moderate head injury.
A police cordon was put in place on State Highway 50A, which is known as the Hawke's Bay Expressway, between Pakowhai Rd and Evenden Rd for about 45 minutes as the double lane blockage was cleared.
Three fire engines were called to the scene and cleared away crash debris before vehicles were allowed back through.