One witness, who only wanted to be known as Naomi, said the police car was travelling at speed up York Pl about 8.30am, without siren or flashing lights, when it collided with a small Mazda Demio.
''As he was coming up the hill, he was all floppy in the vehicle. The car was going quite fast.''
The Mazda then hit a parked Ford Focus, trapping a woman between the two cars.
She said the woman appeared to be headed into the York Pl Preschool and Nursery when she was pinned.
The police car continued on, knocking over a lamppost before colliding with an Otago Road Services school bus, she said.
''I was out walking. It was almost me getting hit. I had to jump out of the way or get hit, too.
''I was thinking 'Oh my God'.''
Once the police car came to a stop, she reached in through the passenger door and tapped the officer on the shoulder.
''He was not responding. He was unconscious. I tapped him and he woke up and he didn't know what happened. He seemed out of sorts.''
York Pl resident Richard Goodall said the policeman was in ''a weird state''.
''When I talked to him, he looked like he'd been knocked out and was wondering how he got on the wrong side of the road.''
Mr Goodall said he woke to three big bangs, ''all in quick succession''.
''We thought it was the rubbish truck making all that racket.''
Otago Coastal area commander Inspector Matenga Gray said the woman pinned between the two cars had moderate-to-serious injuries and was taken to Dunedin Hospital.
''A baby in her care was also checked at hospital but is understood to have minor injuries.''
He said initial information suggested the police officer ''possibly suffered a medical event'', and he was also taken to hospital.
''Police are investigating to determine the exact circumstances of what happened,'' he said.
