French veteran Peterhansel -- known as 'Mr Dakar' -- had been second overnight, 22 minutes and 36 seconds behind the Toyota of Qatar's Al-Attiyah, and was setting the pace in the special stage when he crashed after 212km.
Organisers said co-driver Edouard Boulanger was taken to hospital in Buraydah for further examinations after suffering back pain.
Four times champion Al-Attiyah won the sandy stage, his third victory of this year's event, finishing nearly three and a half minutes clear of France's nine times world rally champion Sebastien Loeb.
Al-Attiyah leads South African team mate Hendrik Lategan by an hour and six minutes in the overall standings.
Triple Dakar winner Sainz, who had been fourth overall at the start of the day, crashed at the same place as Peterhansel, without injury, and was waiting to repair the car before trying to resume the rally.
Saudi Arabia's Yazeed al Rajhi, who had started the day third overall for Overdrive Racing, stopped after 216km with his Toyota suffering mechanical problems.
