"The officer in the vehicle did not look quite right when he zoomed past me. He was sitting way back in his seat with his head right back against the headrest," said one witness, who drove past the officer shortly before he crashed.
The officer was understood to have suffered a "medical event" in the lead up to the crash and remained in critical condition in hospital yesterday, a police spokeswoman said.
According to neighbours who live metres from where the car came to rest, the crash was dramatic.
"It was like a huge explosion when he's hit that retaining wall," one woman, who didn't want to be named, said of the trees outside her front yard. "The whole house shook and we knew it was something big."
Derek Molloy, manager of Wright's Outdoor Equipment Centre across the road from the scene of the crash, witnessed the patrol car as it "shot through at a good rate of knots".
"It was just a straight line and he launched off the kerb and over the retaining wall."
Mr Molloy took off across the road to help. By the time he got there, others, including people who had been waiting for the bus about 10m from where the car ended up, were assisting as well. One man was trying to revive the officer, he said.
"He [the officer] had no colour and had very laboured breathing."
The airbags in the car had deployed, Mr Molloy said.
"It didn't look like he's hit his head on the windscreen or the dashboard."
As those who assisted the officer waited for the ambulance to arrive, his breathing became shallow, his face started losing colour and his lips went blue, he said.
- additional reporting: Susan Strongman
