RESCUERS USING JACKS, saws and wheelbarrows were digging through a caved-in mine tunnel today looking for about 25 workers trapped a day after the collapse at a giant gold and copper mine in Indonesia, the mine operator said.

Four bodies have been found and 10 miners rescued since the cave-in Tuesday morning. Oxygen was being pumped into the tunnel as the search continued, but the status of the trapped workers is not known.

Heavy equipment cannot be used in the tight space, forcing rescuers to remove debris by hand, according to a statement from PT Freeport Indonesia, a subsidiary that runs the Grasberg mine in remote Mimika district in Papua, the easternmost province in the vast archipelago nation. The mine is owned by Phoenix, Arizona-based Freeport-McMoRan Copper & Gold Inc.

Prone to collapse

“We don’t want to be careless because the terrain surrounding the old tunnel is prone to collapse,” said Papua police spokesman Lieutenant Colonel Gede Sumerta Jaya. All of the workers are men, and many of those rescued suffered cuts and broken bones, Sumerta said.

The police spokesman said the cause of the cave-in was unclear. An investigation team from the Indonesian mines and energy ministry was sent to the site, senior ministry official Thamrin Sihite said.

The company said 39 employees and contract workers were inside a classroom in the tunnel undergoing safety training when the accident happened. Three workers escaped unhurt on their own.

Instructor Kristian Sitepu was standing in front of the 5-by-11-metre classroom explaining rescue procedures during an emergency when he heard rumbling above the ceiling.

When rocks started falling, he and those seated in the front row ran and managed to escape unhurt. But he said others were trapped after the only exit quickly filled with rocks and soil. Some were hit and crushed while trying to get out.

They were trapped and shouting for help … but I couldn’t do anything. It hurt me.

He said rescuers arrived a few minutes later with jacks to try to stabilize the tunnel.

Sihite said the training room was built 15 years ago, and about 80 percent of it is now covered by about 190-cubic-metres of debris.

The tunnel itself is about 50 metres long and has five offices, a dining room and three classrooms.

More than 20,000 workers are employed at the mine. In 2011, production was crippled when 8,000 unionized employees walked off the job after demanding higher pay. The strike ended after the company agreed to a 37 percent wage hike and improved benefits.