A unionist mine worker was shot and killed at South Africa's Lonmin PLC (LON:LMI) facility near the town of Marikana, about 75 miles northwest of Johannesburg, in the latest incident connected to the country's platinum industry.

"One of our members was attacked with a gun in our office at Lonmin's Western Platinum mine," said National Union of Mineworkers spokesman, Lesiba Seshoka, on Monday, telling reporters that the worker later died.

Seshoka couldn't confirm who was responsible for the attack and police only confirmed that one person had been killed, and another, the union treasurer, was in a critical condition in a nearby hospital.

Another union spokesman, Mxhasi Sithethi, said two gunmen opened fire outside NUM's offices at around 10 a.m. local time, causing the union worker to flee into the building, according to AFP. "They followed him and killed him," Sithethi said. "There was no confrontation. Nothing."

The attackers then shot the union treasurer at least six times when he confronted them, according to Sithethi. The incident adds to ongoing tensions at the platinum, palladium, rhodium and gold mine, a major driver in the country's economy. South Africa is the world's largest producer of platinum.

Marikana is the same town where police shot and killed 34 miners in August of 2012 in the single deadliest police action since the end of apartheid. Monday's killing is the latest in a recent wave of unrest to hit South Africa's platinum industry.

NUM's former General-Secretary, Cyril Ramaphosa, is now deputy leader of the African National Congress, and was on Lonmin's board when the killings in Marikana happened, yet he later resigned from the board. Tensions in the industrial sector have been fueled by a bitter rivalry between two unions. NUM has faced off with the Association of Mineworkers and Construction Union members, who accuse NUM of being too closely aligned to Lonmin corporate management to protect the interest of workers. AMCU also considers NUM to be allied with the governing ANC party.