Seven people died while undergoing a fitness test used to select prospective candidates for traffic officer posts, the South African Broadcasting Corporation (SABC) reported.
The victims were among tens of thousands of applicants competing for 90 provincial traffic officer posts in Pietermaritzburg, the KwaZulu-Natal Province, the report said.
More than 200 people collapsed while undergoing the test on Friday, and seven of them died, according to the report.
The other people were treated at various hospitals around the city and 11 of them were still in a serious condition, said the report.
More than 35,000 job seekers turned up at the Mkhondeni testing center for the 90 jobs which were up for grabs.
Tragedy struck when groups of job applicants were put on a four kilometre run in over 30 degrees heat. Many collapsed from dehydration and heat exhaustion, according to the report.
Families blame authorities for poor planning and believe that the running test was too tough in the hot weather.
The local government said it would investigate the incident.
"We will have to check whether adequate medical attention was provided, including medical advice to those who were going to run the four kilometres, which would also include the adequate supply of water," said Willies Mchunu, the city's Member of Executive Council for Transport, Safety and Liaison.