A spokeswoman for Freeport Indonesia said the collapse occurred in a training area deep underground at the Big Gossan Mine in Grasberg, Tembagapura, The Wall Street Journal reported. Vice President of Communications Daisy Primayanti said three people were able to get out on their own, and rescuers found four more alive and two bodies.
"The rescue process is difficult and will take some time to complete," she said.
Freeport Indonesia, the biggest taxpayer in Indonesia, is a subsidiary of Freeport-McMoRan Copper & Gold Inc., headquartered in Arizona.
The mining operation has about 24,000 people on the payroll, the BBC reported.