By JEFREY PATTIRAJAWANETIMIKA, Indonesia (AP) â¿¿ Mining activities at a giant U.S.-owned gold and copper mine in Indonesia were halted Wednesday as rescuers using jacks, saws and wheelbarrows dug through a caved-in mine tunnel looking for about 25 trapped workers, the mine operator said. Four bodies have been found and 10 miners rescued since the cave-in occurred Tuesday morning. Oxygen was being pumped into the tunnel as the search continued, but the status of the trapped workers was 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. "We don't want to be careless because the terrain surrounding the old tunnel is prone to collapse," said Papua police spokesman Lt. Col. Gede Sumerta Jaya. All of the workers are men, and many of those rescued suffered cuts and broken bones, Sumerta said. He 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. Meanwhile, hundreds of workers blocked a main road about two miles (three kilometers) from the accident site in solidarity with the victims. "We need a guarantee from the management for our safety in working underground," said Ronald Waromi, an action organizer. 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-meter (16-by-36-foot) classroom explaining rescue procedures during an emergency when he heard rumbling above the ceiling.