About 12.05 on Sunday, March 17 NSW Ambulance paramedics responded to reports of a multi-vehicle collision on the Princes Highway, near the Caltex service station in Milton.

A 19-year-old male, driving a ute, was found unconscious in his vehicle by bystanders following a crash with a caravan being towed by a second vehicle, a NSW Ambulance spokesperson said.

"The car was extensively damaged. The patient awoke and was assisted from the vehicle by bystanders," the spokesperson said.

Paramedics treated the patient for head and leg injuries before transporting him to Shoalhaven Hospital in a serious condition. Three other patients in two other vehicles were assessed on scene and were not transported, the spokesperson said.

The Princes Highway was closed for a short period.

About 1.30am on Sunday morning, emergency services responded to a single vehicle accident where a car rolled over on Woodstock Road, south of Wheelbarrow Road.

The male driver, a sole occupant of the vehicle, was ejected from the vehicle, a NSW Ambulance spokesperson said.

He was found on the road by another driver who came across the accident. The driver suffered a serious leg injury. 

Paramedics stablised the patient on scene before transporting him to Moruya Airport to meet the South Care Helicopter. 

The helicopter was unable to land in Milton due to poor weather, a spokesperson said. The male was flown to Canberra in a serious but stable condition.