Police have said the teenage girl found dead near Belfast City Hospital, named as 17-year-old Tara Wright, was injured in an earlier one-car crash.
The girl was pronounced dead after being found in a grey coloured MG car just before 3am on Sunday, close to the hospital on the Lisburn Road in south Belfast.
A short time earlier, police had been alerted to a silver Mercedes on its roof in undergrowth near a roundabout on the Ballygowan Road in Castlereagh.
A man was found badly injured near the scene and was taken to hospital for treatment.
PSNI Inspector Nigel Henry said: “Firstly, I would like to extend my sympathies to the family of Tara at this very sad time.
“Our investigation is at an early stage - however, we do believe that Tara was injured during the one-vehicle road traffic collision on the Ballygowan Road.
“We are appealing to anyone who witnessed either the silver Mercedes or grey MG to contact us to assist us with our enquiries.”
Officers believe the girl was taken to hospital in the MG and that the vehicle may have been spotted between the Ballygowan Road and the Lisburn Road.
Four men - aged 20, 21, 28 and 30 - were arrested on Sunday and have since been released on bail.