Two teenagers had to be cut free from a car after it left the road and ploughed into woods.
Crews from Thames-side used specialist hydraulic cutting equipment to free the boys from the front of the wreckage which crashed in Wrotham Road, Meopham, at around 10.45pm on Wednesday.
Two other teenagers had freed themselves from the vehicle before firefighters arrived.
The two in the front were taken to Darent Valley Hospital by ambulance.
The 17-year-old driver has been discharged, while the passenger, 18, remains in a critical but stable condition in hospital.