Two police officers were shot and wounded in a shootout on the M2 highway in Johannesburg on Tuesday afternoon, Gauteng police said.
Lt-Col Lungelo Dlamini said the officers, aged 30 and 37, were patrolling the highway when they spotted four suspicious men in a Mercedes-Benz.
"When they tried to pull it [the car] off the road, the occupants started firing shots at them with assault rifles (possibly R5s)," Dlamini said.
"The officers were both shot in the upper body. The suspects then drove away."
The officers were rushed to a nearby hospital.
Dlamini said police were searching for the four men.
Just before 2pm, one of the officers could be seen lying on the ground while paramedics attended to him.
A large police contingent, with weapons drawn, appeared to be searching the area for the men.
A police helicopter hovered close to the ground, while traffic ground to a halt on the busy highway.
Many motorists pulled their cars over to the curb to see what was happening.
One man pointed to a bullet-hole in his rear windscreen and said he had been driving past when he heard a gunshot.
"I am lucky to be alive," the man said. He asked not to be named.