South Africa's Olympic double amputee Oscar Pistorius shot his girlfriend dead after mistaking her for a burglar, according to reports.
Pistorius, known as "The Blade Runner", allegedly killed his girlfriend at 4am (1pm AEDT) on Thursday morning local time at his home in Pretoria, the Die Beeld website reports.
Police captain Sarah Mcira confirmed that a woman was shot four times in the arm and the head.
She was declared dead at the scene.
Die Beeld has named the victim as his girlfriend of a year, Reeva Steenkamp.
Steenkamp is a model who has posed for FHM and described herself on her Twitter page as a "SA Model, Cover Girl, Tropika Island of Treasure Celeb Contestant, Law Graduate, Child of God."
South African journalist Kalay Maistry told Sky News that it is believed his girlfriend was trying to surprise him for Valentine's Day.
"I think what this actually highlights is the level of fear ordinary South Africans have," she said.
"This is a man who has gone to bed, it's an innocent surprise from a girlfriend … and the moment he thinks someone is trying to break in he grabs his gun."
Yesterday Steenkamp tweeted a now-eerie Valentine's Day message.
"What do you have up your sleeve for your love tomorrow??? #getexcited #ValentinesDay," she wrote.
Pistorius was arrested at the house and is expected to appear at Pretoria Magistrate's Court later today.
A case of murder is now being investigated.
His agent Peet van Zyl said he was on the way to Pretoria to speak with him.
"Oscar is a humble person and a lovely guy — I'm sure what's happened has been a terrible mistake but I really don't have the details at the moment," he said.
He is reportedly in shock.
A 9mm pistol was taken from the scene.
Pistorius became the first athlete to compete at both the Olympics and Paralympics in London last year.
He was due to compete in able-bodied events in Sydney and Perth early next month.