Gunmen fired at a bus carrying workers of US mining giant Freeport on Saturday in Papua province, wounding two Indonesian security guards, police said.
Ambushes near the world's largest gold mine since mid-July have left three dead, including a 29-year-old Australian, and more than a dozen wounded.
Around four gunmen ambushed the bus on its way to drop off workers for the morning shift, Papua police spokesman Lt Col Agus Rianto said.
A security guard was shot in the thigh and another was hurt by broken glass, but both were in stable condition at a nearby hospital, he said.
Police are searching for the gunmen, who fled into the jungle, Rianto said.
A Freeport spokesman could not immediately be reached for comment.
The Freeport mine has often been targeted by arson, roadside bombs and ambushes since production began in the 1970's in underdeveloped Papua, home to a low-level separatist movement of thousands of kilometres from the capital, Jakarta.
Police have arrested seven suspects in the ambushes so far, including two Freeport employees, who face charges of premeditated murder and illegal weapons possession.
It is difficult to get accurate information out of Papua, a highly militarised area that is off-limits to foreign journalists.