The crash occurred Friday afternoon in central Phnom Penh, The Phnom Penh Post reported.
The suspect, Keam Piseth Narita, 23, allegedly drove her car into a crowd of motorbikes, cyclists and pedestrians outside the Ministry of Interior.
Three children were killed, six people were seriously injured and two others were slightly injured as a result of the crash, officials said.
Before the crash, Narita allegedly led police on a high-speed chase after she hit a motorbike, municipal traffic police chief Pen Khun said.
On Sunday, the Penh Municipal Court charged Narita with "intentional driving causing death and serious injury." The maximum penalty for a fatal hit-and-run is up to three years in jail and a fine of between two and $1,500 if convicted.
Hit-and-run crashes account for about 50 percent of road fatalities in Cambodia, Handicap International said.
The trend is rising, officials say, because many drivers fear witnesses will resort to a form of "citizen justice."
"Drivers who are involved in a crash are afraid that if they stop that people will hit them or kill them. So most drivers try to run away in order to save their own lives," said Road safety program manager Ear Chariya.
He said witnesses often turned to mob violence because they do not trust that authorities will deliver justice.