The 50-year-old from Murray Bridge was killed when the car she was driving left the Old Princes Highway and rolled at about 6.30pm.

She was airlifted to the Royal Adelaide Hospital after suffering head injuries but died a short time later. Tuesday proved another deadly night on South Australian roads.

Just over two hours later three young males were killed when the car they were travelling in left the road at Mount Compass and hit a tree.

Two 18-year-olds and a 17-year-old from Mount Compass were killed in the crash while the 17-year-old male driver was taken to the Flinders Medical Centre with minor injuries.

The accidents have brought the State’s 2010 road toll to 19, compared to five at the same time last year.

The first month of 2010 is now the most deadly January since 1999, when 20 people were killed on South Australian roads.

This January also ranks among the most deadly months for drivers in the last 10 years, compared to 27 road deaths in March 2005, 18 in July 2004 and 20 in May last year.