33 worshippers had joined church rituals on the banks of the Jukskei River when flash flooding struck on Saturday and casualties were all part of congregation.
Bodies of two victims were found that day and another seven on Sunday. The priest who was presiding at the rituals survived.
Religious groups frequently gather along the Jukskei River, which runs past townships such as Alexandra in the east of Johannesburg, for baptisms and ritual cleansing.
Mulaudzi said Sunday that officials had warned residents about the dangers of conducting the rituals along the river.
“We have been receiving a lot of rain on the city of Johannesburg in the last three months, and most of the river streams are now full,” Mulaudzi said during a news briefing.
He added: “Our residents, especially congregants who normally practice these kinds of rituals, will be tempted to go to these river streams.
“Our message for them is to exercise caution as and when they conduct these rituals.”
Rescue workers and firefighters are still searching for the missing people, with emergency services indicating the chances of finding them alive are fading.Sudden surges of water are common in this part of Johannesburg, where storms take place almost every night during the southern summer.
Mulaudzi confirmed that people have free access to rivers and practise their religion where they wish, but awareness campaigns need to be intensified ‘to avoid such tragedies’.