South African paralympic star Oscar Pistorius is being questioned by South African police for shooting dead his girlfriend at his home in Pretoria, domestic media said on Thursday.
Johannesburg's Talk Radio 702 said Pistorius was understood to have shot his girlfriend in the head and arm, although the circumstances surrounding the incident were unclear.
He may have mistaken her for a burglar, the radio report said.
A police spokeswoman told Reuters that a woman had been found dead at the house but declined to give any more details.
Pistorius, who races wearing carbon fibre prosthetic blades after he was born without a fibula in both legs, was the first double amputee to run in the Olympics and reached the 400 semi-finals in London 2012.
South Africa has some of the world's highest rates of violent crime and some home-owners carry weapons to defend themselves against intruders.
Pistorius allegedly shot and killed his girlfriend in the early hours of Thursday morning, apparently after thinking she was an intruder, Beeld reported.
South African media are reporting the incident happened at his Silver Lakes home at around 4am on Thursday morning.
Captain Sarah Mcira confirmed to a South African website that Pistorius's girlfriend was shot in the head and arm and died at the scene.