"Unidentified gunmen opened fire and three people were killed and one was wounded", Ramdani Sirait, a spokesman for Freeport's Indonesian subsidiary, told AFP.
He added that one of the victims was a Freeport contract worker and that the identities of the three others was not immediately known. All were shot inside the mining area, he said.
The Grasberg mine in the eastern Papua region, operated by Freeport McMoRan and one of the largest in the world, has been plagued by trouble since miners declared a strike over wages on September 15.
Also on Friday, an AFP correspondent in Timika saw Indonesian lawmakers meeting Freeport officials at the city's Rimba Papua hotel.
Following that meeting, officials representing the miners sat down with Freeport management in talks mediated by the labour ministry, the correspondent reported.
"The company wants us to stop the strike while the negotiation is on going. But we will never do so if they don't accept our demand," the workers spokesman Virgo Solossa told AFP.
The strikers, mostly indigenous Melanesians, say they are the lowest paid Freeport workers in the world, earning between $1.50 and $3.50 an hour.
They are demanding an eight-fold increase. The company has offered a hike of around 25 percent.
Grievances by strikers erupted into deadly violence this month when workers clashed with police and gunmen targeted contract workers brought in to replace striking miners.
More than 8,000 of Freeport's 23,000 workers have been on strike, vowing to stay away from work until November 15.
The AFP correspondent said that hundreds of striking workers were still blockading two entry points to the sprawling Grasberg facility, with only one gate still open and under heavy guard by military and police personnel.
Sirait said the latest killings occurred near a shooting last Saturday when three contract workers were killed in similar circumstances.
"Police are now investigating the case," Sirait said.
In addition, two mine workers were killed in an October 10 clash between police and striking miners.
The dispute, coupled with strikes at Freeport's South American mines, has raised concerns of a copper shortage, but analysts say any impact could be limited by falling demand for the metal.