Pretoria, South Africa (CNN) -- A beloved model is dead, those who knew her are in mourning, and one of the world's most admired Olympians is charged with her murder after a Valentine's Day shooting in South Africa.

Oscar Pistorius, a Paralympic runner who blazed new terrain by competing in last summer's Olympics, is accused of killing his girlfriend, Reeva Steenkamp. A shooting took place inside his upscale home in Pretoria, South Africa, early Thursday, and only the two of them were there at the time, police said.

Shockwaves from the incident quickly reverberated across the world, casting a shadow over the man known as the "Blade Runner" for his achievements on prosthetic limbs.

Pistorius will be named officially as the suspect when he appears in court Friday, in keeping with South African law. Authorities have already announced that the suspect is Pistorius' age.

Investigators gave no motive for the alleged killing.

A police spokeswoman said there had been "previous incidents" at the home, including "allegations of a domestic nature."

Police were alerted to the shooting by neighbors, and residents had "heard things earlier," spokeswoman Denise Beukes said.

Some South African media outlets said the woman was mistaken for an intruder. South Africa has a high crime rate, and many homeowners keep weapons to ward off intruders.

Beukes said those reports did not come from police. There did not appear to be signs of forced entry at the home, she added.

"This is a very quiet area and this is a secure estate," Beukes said.

A pistol was recovered at the scene, police said.

Pistorius made no public statement. His spokeswoman Kate Silvers said the athlete is "assisting the police with their investigation but there will be no further comment until matters become clearer later today." Police also said Pistorius is cooperating.

He arrived Thursday at a police station in Pretoria.

Beukes said the state will oppose bail. So the 26-year-old, who was among the men featured in People magazine's "Sexiest Man Alive" issue, could be behind bars, at least temporarily.

Pistorius is not being brought to court Thursday because the public prosecutor needs more time to prepare the case, police spokeswoman Katlego Mogale told CNN.

Steenkamp, 29, had been looking forward to Valentine's Day, encouraging her Twitter followers to "get excited" for the holiday.

"She was the kindest, sweetest human being; an angel on earth and will be sorely missed," Capacity Relations, the agency that represented her, wrote on Twitter.

She was "just a great, fun presence of a person," said Hagen Engler, former editor of the magazine FHM. He described her as "a bikini model, beautiful, gorgeous girl" with a "wicked" sense of humor. She understood the industry and was intelligent and fun to work with, he said.

Pistorius' father, Henke, told the South African Broadcasting Corp. his son was "sad at the moment."

"I don't know nothing. It will be extremely obnoxious and rude to speculate," the father said. "I don't know the facts."

Pistorius, a double amputee, competed against able-bodied runners during the London Olympics, triggering controversy as some said the prosthetic limbs gave him an advantage. His legs were amputated below the knee when he was a toddler because of a bone defect. He runs on special carbon fiber blades.

Pistorius was initially refused permission to enter the Olympics, but he hired a legal team to prove that his artificial limbs did not give him an unfair advantage -- and was allowed to compete.

While he did not win a medal, his presence on the track was lauded by many people around the world as an example of victory over adversity and dedication toward a goal.

He smashed a Paralympic record to win the men's 400m T44 in the final athletics event of the 2012 Games.Olympian Charged With Murder of Model Girlfriend