Pretoria - Mechanical engineer Sibusiso Langa, who is accused of killing a group of joggers in Midrand, tried to leave the scene of the accident, the North Gauteng High Court in Pretoria heard on Monday.
Doctor Zulu was testifying in the trial of Langa, 46, who has pleaded not guilty to five charges of murder, one of attempted murder and one of driving under the influence of alcohol.
"He climbed back into his Mercedes and then tried to start it. He could not get it started," Zulu told the court.
"A tow vehicle arrived at the scene and stopped next to him. The doors of the truck were standing open and the driver of the Mercedes then tried to get into the tow truck.
"I alerted the driver of the truck who rushed to his truck and removed the keys," he said.
Zulu said Langa walked away from the scene when the metro police arrived, and they had to chase after him in their car to bring him back.
Reneilwe Lesenyeho, 31, Gaolojwe Isaac Tlale, 37, Moroesi Margeret Mokoatsi, 35, Given Mills, 30, and Nomvula Regina Dumako, 35, died and Abegail Stengile nearly died when Langa allegedly hit them while they were jogging on the gravel next to Lever Road, in Midrand, on 22 October 2011.
Trevor du Toit told the court he saw a man in a Mercedes-Benz driving erratically near Lever Road that morning.
While fiddling with something in his car, the driver crossed the yellow line and, at one stage, stopped in the middle of an intersection at a red light.
Zulu testified that six joggers passed him while he was walking to work early that morning.
Ploughed into them
They were jogging on the gravel next to the road when he heard a car approaching at speed.
"When the vehicle approached the corner, the driver couldn't control it. It drove straight at the people and it drove into those people and knocked them down," he told the court.
"As the vehicle ploughed into them I saw them being thrown into the air and dropping down.
"Five of those people died as a result. He knocked down the five almost at the same time.
"I immediately tried to call the police or an ambulance. The driver of the vehicle alighted and went to check the vehicle in the front.
"I asked him why didn't he assist the lady who was crying... Why kill people in this manner in front of me?
"His response was that these people's behaviour surprised him."
Zulu said Langa's trousers were wet in front, but that he had no injuries and appeared to be either drunk or sleepy.
He testified that he had seen the accident clearly, that the joggers were not in the road when they were hit and that no other car was involved.
Accident investigator Johannes van Loggerenberg testified that he saw a sock still stuck to the vehicle, which had human remains and blood on its right side and roof.
It was clear from the damage to the vehicle that there had been a severe impact.
Langa did not have any visible injuries, but his eyes were bloodshot, he looked sleepy and there was a strong smell of alcohol on his breath.
Johannesburg metro police officer Sibongile Makhubela, who chased after Langa as he was leaving the scene, testified that she asked him why he had driven over those people.
"He told me they were in the way.
"He was unsteady on his feet... He was slurring his words. His eyes were bloodshot and his breath smelled of alcohol," she said.
Langa's advocate Richard Mkhabela put it to her that Langa was "not that drunk", because he was able to hand over his identity document.
The trial continues.