The chased vehicle lost control navigating corners and struck a traffic management worker, who was with a team working on powerlines.
It appeared the three occupants of the vehicle took off after it stopped.
The police car stopped by the stricken worker and an officer provided first aid until emergency services arrived, while the second police officer chased the driver.
Police were out in force and the road was temporarily blocked.
The worker, aged in his 20s, was flown to hospital in the Westpac Rescue Helicopter and is in a serious condition.
Meanwhile, a police dog team arrived and found a man suspected of involvement, who is now "helping police with their inquiries".
A man at the nearby Cosmopolitan Club, who didn't want to be named, said two men came running through the carpark after the worker was hit.
They ran south down nearby George St.
The man said there were lots of police and dog handlers looking for duo.
As with any fleeing-driving incident, the Independent Police Conduct Authority has been notified.