Four gold miners trapped underground after a tremor caused a rockfall in northeast South Africa have been found dead, their union said Sunday.

A fifth miner was rescued with serious injuries on Friday after the accident at the Tau Lekoa Mine in the town of Orkney, the National Union of Mineworkers (NUM) said.

“The four mineworkers were found dead,” a union statement said after the rescue team lost contact with the four men deep underground early Saturday.

“The last person we talked to said: ‘We are suffocating please, bring us some oxygen’,” said NUM president Joseph Montisetse.

Deadly accidents involving miners are common in South Africa, which has the deepest mines in the world.

Last year 81 people died in the country’s mines, according to the department of mineral resources. (AFP)