Accidents in disused mines are common in Zimbabwe, where artisanal or small-scale miners defy authorities by mining in old shafts that are prone to collapse.
The latest incident happened in Chegutu, some 100 km (62 miles) west of the capital Harare on Friday.
Vice-President Constantino Chiwenga told the local Sunday Mail newspaper 13 had died in the collapse at the site which had not been properly sealed off.
Deputy mines minister Polite Kambamura could not say how many people were still trapped underground after the 700 meter-deep mine collapsed.
“The problem is that there was no proper register to ascertain how many people entered,” Kambamura said. “We are sending another team to assess the situation. We want to account for everyone.”
State broadcaster ZBC on Friday reported that 34 miners were trapped underground out of which 13 had managed to escape.
Dozens of distraught family members waited in tents, hoping for news of relatives.
“The most painful thing for me is not knowing if my son is dead or alive…I can’t take it anymore knowing that he is down there,” said a weeping Memory Gohwe, whose son remain trapped.
Some worried relatives already feared the worst.
“To be honest we have lost any hope of getting any survivors,” said Omega Jonera, nine of whose family members were trapped underground.
Reporting by Tonderai Gonorenda in Chegutu and Nyasha Chingono in Harare, Editing by Bhargav Acharya and Alexander Winning