Updated

South African Olympic sprinter Oscar Pistorius will remain in jail until a court appearance Friday after allegedly shooting and killing his girlfriend on Thursday.

Reeva Steenkamp, a model who was 30 years old, was shot and killed Thursday morning.

Police in Johannesburg confirmed a shooting at the runner's home in a suburb of the capital city early Thursday morning, but South African laws prohibit a suspect from being officially identified until appearing in court.

Various reports indicate Pistorius may have mistaken her for a burglar. She apparently entered Pistorius' home at around 4 or 5 a.m., local time. There has been speculation that Steenkamp might have been trying to surprise Pistorius for Valentine's Day.

Police said an investigation is ongoing.

"The SA Police Service were just as surprised this morning to hear on the radio that allegations had been made that the deceased had been perceived to be a burglar," said police spokeswoman Brigadier Denise Beukes. "We were very surprised and those allegations did not come from us."

Steenkamp had recently written on her Twitter account that she was looking forward to Valentine's Day, writing "What do you have up your sleeve for your love tomorrow???"

The two had reportedly been dating for about a year.

Pistorius, known as the "Blade Runner," made history at the London Olympics last year when he became the first double-amputee runner to compete in the Games.

The 26-year-old Pistorius had both legs amputated before he was a year old after being born without fibula bones and runs on prosthetic blades.

The International Association of Athletics Federations (IAAF) had initially said that his prosthetics were considered technical aids and in violation of an IAAF rule. But the Court of Arbitration for Sport later overturned that decision, making him eligible to compete against able-bodied runners.

Pistorius qualified for South Africa's Olympic team in 2012 and competed in the 400-meter race, reaching the semifinals, and the 1,600-meter relay.