The car that hit the broken-down vehicle ended up on the wrong side of the road where it was struck by a third vehicle and landed on top of Toni hi.
It was not known which of the two impacts killed her - she was found dead after a tow truck lifted the car off her.
Hart lay critically injured on the roadway and was given aid by a passing nurse until ambulances arrived.
He died hours later in Napier Hospital's intensive-care unit.
He was 35, leaving a wife and two sons.
The remaining occupants in the broken-down car, two Hastings sisters, were sheltered from rain in the third vehicle until ambulances arrived and were taken to hospital. One suffered concussion and the other minor injuries.
The three-car-crash happened on Embankment Rd, now largely a walkway after the bridge over Ahuriri Estuary was built.
Hart was stationed at Hastings and then Waipawa before resigning from the police force to work on his father's farm in Tutira until six months before his death, when he re-joined the police and was stationed in Napier.
Dame Patsy Reddy, Governor-General of New Zealand, will attend the national ceremony at Royal New Zealand Police College (RNZPC), her first official engagement as Governor-General.
This year the 32 officers slain on duty and 40 officers and employees who have died as result of duty since 1886 will be remembered, along with serving and former constabulary staff and employees who have died in the past year.
Constable Glenn McKibbin was shot dead while on duty in Flaxmere in 1996 and Senior Constable Len Snee was gunned down during the Napier siege in 2009.
In 1984 constable Graeme Wackrow, based in Dannevirke, died as result of injuries received in a crash on SH2 south of Dannevirke.
In 1940 constable Richard Byrne died as a result of injuries received in a crash in Napier.
In 1897 Constable Alfred Stephenson and Sergeant Florence O'Donovan drowned while rescuing people from floods in Napier.
Police Remembrance Day is held annually on September 29, the feast day of the patron saint of police Archangel Michael.