A third person from the same car has been taken to hospital following the incident near the village of Iwade.
One of the victims is believed to be a young girl, whose boyfriend is thought to have been injured.
Friends of the girl were seen leaving flowers and other tributes at the scene, with one saying she had ‘known her all her life’.
Emergency services were called to the scene at around 8.30pm on Saturday, with police, ambulance and the fire service attending.
The car was later recovered from the river.
Three other vehicles, understood to be from separate crashes, were in the river nearby.
Images from the scene showed a corner of a blue car encased in ice in the river, with a wheel above the surface.
Temperatures have regularly dropped below freezing in Kent across this weekend as wintry weather descends across the country.
While the south-east county is not covered by a weather warning for snow and ice this evening, large parts of southern England are.
The Met Office said the low temperatures would make driving conditions dangerous, and urged people to give themselves extra time for their journey.
