A driver who mowed down a cyclist and a pedestrian outside Melbourne's St Paul's Cathedral on Thursday night refused to stop her car after being confronted by several people.
The driver, a 32-year-old woman of no fixed address, was arrested about four hours after she allegedly hit two people on Flinders Street during peak hour.
She was taken to hospital for a mental health assessment, police said.
A witness, who did not want to be named, said he was cycling down Swanston Street when he saw a white car with no numberplates drive through a red light and hit a 47-year-old South Yarra man who was walking across Flinders Street near the cathedral about 6.30pm.
Moments later, the car struck a 48-year-old cyclist from Bentleigh East at the intersection of Swanston and Flinders streets.
The witness said the cyclist was thrown from his bike and left lying on the side of the road.
"I saw the driver stop briefly and people who witnessed the crash ran up to her window to speak to her, but then she just drove off, it was really the most peculiar thing," he said.
The man and another witness then chased the driver who stopped again at the next set of traffic lights.
He said the car windows were covered in fog and the driver seemed disoriented.
"We caught the driver at the next set of lights and we tried to get them to stop but she just looked at us and then drove off again," he said.
"It was almost like she wasn't aware of what had just happened."
The man said he had feared for the lives of both the pedestrian and the cyclist.
"They were struck really hard by the car and [they] appeared to be in a really bad way," he said. "Everybody who saw the incident was just completely stunned by it."
An Ambulance Victoria spokeswoman said one man was taken to The Alfred hospital in a stable condition, while a second man was treated by paramedics at the scene.
Police arrested a 32-year-old woman just after 10pm on nearby Flinders Lane in relation to the incident.
Anyone needing support can contact Lifeline on 131 114.