A father and son who were onboard a light plane when it crashed into a paddock in South Australia’s mid-north have died.

The Cessna light aircraft struck powerlines and crashed in a field on Mumfords Road at Merriton, near Crystal Brook, just after 4pm on Sunday. 

The pilot, 50-year-old Ben Mumford and his 24-year-old son Charlie Mumford, both from Redhill, were pulled from the wreckage by witnesses. 

Ben Mumford was taken to the Royal Adelaide Hospital with life-threatening injuries, but this morning police confirmed he died overnight.

Last night, police said the passenger, Charlie Mumford, died at the scene

The crash happened just after 4pm on Sunday. (ABC News.)

The crash sparked a grass fire which was extinguished by the Country Fire Service and local farm units.

Investigators from the Australian Transport Safety Bureau (ATSB) are expected to examine the crash site later today. 

“We expect to be there for the next couple of days while we try to piece together all of the information, not only from the site itself, but equally any other recorded data, witness statements, maintenance records,” ATSB Chief Commissioner Angus Mitchell said. 

“We don’t put a timeline on this, but it’s likely to take anywhere up to around four weeks before we have all of that evidence together. 

“What we do with the evidence then really depends on what we’ve found and how complex the investigation may be, but we do hope to have some early indications within that first four to six weeks.” 

Posted , updated