Harmony Gold Mining Co. rescuers have recovered the bodies of eight workers after an underground rockfall in South Africa’s worst gold mining disaster in five years. One worker is still sought after eight others were evacuated Wednesday.

The rockfall was triggered by a fire and seismic movement, according to company officials; operations at Doornkop, 19 miles west of Johannesburg, have been suspended. A prolonged shutdown of the mine, representing 10% of output, could deeply affect Harmony; last year, it produced 3,631 kg of gold.

Search and rescue teams, along with deep-level firefighters, first deployed at 6 p.m. on Feb. 4 after the flames erupted 5,700 feet down the single-shaft mine, said a Harmony spokesman. The eight survivors were brought up from a refuge chamber uninjured on Wednesday.

A 2.4-magnitude tremor that caused the rock fall damaged power cables, said the National Union of Mineworkers (NUM) officials quoted by Reuters News; ventilation and water pipes were heavily impacted, too.

Once the last worker is located, firefighters will first fully extinguish the flames, Department of Mineral Resources representatives said. Regulators will determine follow-up steps upon subsequent inspection completion.

To this end, Mining Minister Susan Shabangu pledged “thorough investigations” to reporters at the mine, alongside Harmony Chairman Patrice Motsepe who skipped the Mining Indaba conference for the rescue. “We must get to the bottom of what caused this to prevent similar occurrences in future.”

Doornkop, which lies in a rich but extremely deep seam, witnessed two 2012 deaths, although none transpired last year. Overall, this was the single-deadliest incident involving company employees in Harmony history. In 2009, though, more than 80 artisanal miners perished at an abandoned, Harmony-owned shaft. The Johannesburg-based company is South Africa’s No. 3 bullion producer.

This incident is the worst in the country’s industry since nine miners died when an elevator cable snapped in 2008, in the shaft of Gold Fields Ltd.’s South Deep mine. In all, the country saw 112 mining industry deaths in 2012, according to the Chamber of Mines, the most recent year for which statistics are available.