Police are seeking witnesses after a fatal smash at Houghton in the Hills.

Two Lancers were allegedly speeding and collided with a Toyota van on North East Road, late Sunday afternoon.

A Birdwood man, 68, was injured and later died in hospital.

It’s possible the two drivers involved were drag racing but neither was side by side at the time.

Two men, 26 and 21, have been charged with dangerous driving. One was refused bail while the other man was allowed bail

Meanwhile a man 22 who died after his motorcycle crashed into a car at Woodside came from Reynella.

Police say the rider collided with the rear of the vehicle on Onkaparinga Valley Road late Friday afternoon.

Poor weather conditions are believed to have contributed to the crash.