"It's so shocking that the last words I said to her were, 'Where's my lunch money, Mum?' She said, 'Go look in my bag.' I got the money out and she said, 'Have a good day at school, son.' That was the last time I saw her.
"I'm sad I didn't get to kiss her before I left. I would have if I'd known what was going to happen."
Sio said he did not find out about the accident until the afternoon, when an aunt told one of his tutors.
He said his father didn't remember anything from the accident.
"He's okay. He's talking now but he's really, really gutted."
The family were having a meeting and cleaning the house in preparation for the return of Mrs Onesi's body.
Sio said he did not know many details about the crash and was trying to stay strong for his siblings, aged 16, 11 and 9.
Mrs Onesi, aged in her 40s, was a passenger in the family's four-wheel-drive when it and the police car collided on Ormiston Rd about 8.40am.
She died in an ambulance on the way to Middlemore Hospital.
Sione Onesi and the police-car driver were taken to Middlemore with minor injuries and later discharged.
The couple were heading to clean the Otara Tongan Methodist Church as Mrs Onesi did every every Wednesday. Her brother, Vaikoloa Kilikiti, is a pastor at the church.
It is thought the couple were turning into the church grounds when their Pajero was hit and smashed into a power pole before coming to a stop against a concrete fence.
Mrs Onesi was thrown from the vehicle.
The police officer, who had his lights and sirens going, was on his way to a burglary at a house in Preston Rd. The offenders were still at the scene. One person was in police custody last night in relation to the burglary.
Counties Manukau district commander John Tims would not say how fast the squad car was going, but said officers were highly trained drivers.
"But of course there's some responsibilities for the driver. They're legally responsible for any actions, and they have to take a balanced approach between police and public safety when driving in these conditions."
Yesterday's fatal crash was the second of its type involving a police car and a civilian vehicle since 1994, Mr Tims said.
"This incident is every police officer's worst nightmare. Our staff come to work every day to keep our communities safe. We never want something like this to happen.
"The police officer involved is distressed and shocked."
Mr Tims said an independent investigator from another region would study the crash, and the Independent Police Conduct Authority and the coroner would carry out their own investigations.
- Additional reporting: APNZ
