Operations at Freeport-McMoRan’s Grasberg copper mine in Indonesia were suspended after a car collided with a mining truck the day before, leaving four workers dead.

The accident happened at the local unit of Phoenix-based Freeport-McMoRan Copper & Gold Inc., which has been mining copper and gold in the Papua province of the island of New Guinea since the late 1960s The Wall Street Journal reported. 

"Work safety is the priority of PT Freeport Indonesia, and because of that activities at the open-pit Grasberg Mine are suspended for investigation," the company's spokeswoman Daisy Primayanti said after the accident.

The company said nine workers were involved in the accident. Five were being treated at a local hospital, and two have since been discharged.

The massive mining operation has some of the world's largest copper and gold deposits. It produced 885 million pounds of copper and 1.1 million ounces of gold last year.

This is the second fatal accident this month at the mine. A boulder fell and killed a worker underground earlier this month. The company didn't halt operations over that accident.

The company was ordered by the Indonesia government to halt mining at the Grasberg Mine in May of 2013 after 28 workers were killed when an underground tunnel collapsed. The accident occurred outside of production areas, but Freeport halted operations at all of its area mines.

Freeport Indonesia had stopped exports of copper concentrate for eight months in a dispute over terms with the Indonesian government. It resumed exports in August after it agreed to pay export taxes and higher royalties, and reduce the size of the concession area.