The bodies of seven men were found dumped on the Puttfontein offramp next to the N12 highway in Benoni on Thursday night.
Police said they all had bullet wounds and one body had burn wounds.
Gauteng police spokesperson, Colonel Noxolo Kweza, said they are busy trying to identify the victims.
"It is suspected that the males might have been killed underground and might be part of the on-going illegal mining activities," she said.
Kweza said police were alerted by a passer-by who made the grim discovery.
- African News Agency (ANA)