CNN  — 

Five miners died in a South African copper mine Sunday after a fire trapped the workers underground, the country’s Association of Mineworkers and Construction Union said.

One miner was still trapped in the Phalaborwa Mining Company in Limpopo, north of Johannesburg, the union said.

The fire began on Sunday around 1:25 a.m., according to the union. The workers were ordered to evacuate to the nearest refugee chamber, a protective chamber, the union said.

A team later found the bodies of two miners, and a survivor, but high temperatures, which reached 67 degrees Celsius (roughly 152 degrees Fahrenheit), made rescue efforts difficult, the union said. The bodies of three mine workers were later recovered from the chamber, the union said.

The injured worker was taken to a hospital, according to the union.

“The search for one employee continues and an investigation will commence once the last remaining employee is found and the fire underground has been contained and the area declared safe,” South Africa’s Department of Mineral Resources said on Twitter.

Mining safety is an ongoing concern in South Africa.

The latest incident comes two months after seven miners died in a cave-in at the Masakhane gold mine, west of Johannesburg at the Sibanye-Stillwater’s Driefontein operation. An earthquake led to the cave-in.

In February, more than 900 miners were rescued after being trapped in a mine for at least 24 hours following a power loss after a storm in Theunissen in the province of Free State.

CNN’s Darran Simon, Flora Charner, Joe Sterling and Ben Wescott contributed to this report.