The Saintfield Road, Lisburn, which was closed following a serious crash in the area earlier this morning, has reopened to traffic.
Police and ambulance personnel were tasked to the four-vehicle collision near the M1 roundabout, on the outskirts of Lisburn, shortly after 8:30am.
According to the NI Ambulance Service, one rapid response paramedic, one doctor and one emergency crew were tasked to the incident.
One patient was transferred to the Royal Victoria Hospital in Belfast for treatment.
Police said four males - two aged 16, one 17-year-old and a 23-year-old man - have been arrested in connection with the incident.
They are being questioned on suspicion of a number of offences including dangerous driving, using a motor vehicle without insurance and aggravated vehicle taking causing damage to the vehicle.
The busy road was closed for a time and there was significant traffic disruption in the area.
However, the crash has now been cleared and the route has reopened.
PSNI Road Policing tweeted: "The Saintfield Road in Lisburn has now reopened following an earlier road traffic collision."