KABUL, Afghanistan – They hiked for more than 10 hours over rugged mountains — unarmed and without security — to bring medical care to isolated Afghan villagers until their humanitarian mission took a tragic turn.

Ten members of the Christian medical team – six Americans, two Afghans, one German and a Briton – were gunned down in a gruesome slaughter that the Taliban said they carried out, alleging the volunteers were spying and trying to convert Muslims to Christianity. The gunmen spared an Afghan driver, who recited verses from the Islamic holy book Quran as he begged for his life.

Team members — doctors, nurses and logistics personnel — were attacked as they were returning to Kabul after their two-week mission in the remote Parun valley of Nuristan province, about 160 miles north of Kabul. They had decided to veer northward into Badakhshan province because they thought that would be the safest route back to Kabul, said Dirk Frans, director of the International Assistance Mission, which organized the team.

The bullet-riddled bodies — including three women — were found Friday near three four-wheel drive vehicles in a wooded area just off the main road that snakes through a narrow valley in the Kuran Wa Munjan district of Badakhshan, provincial police chief Gen. Agha Noor Kemtuz said.

One of the dead Americans had spent about 30 years in Afghanistan, rearing three daughters and surviving both the Soviet invasion and bloody civil war of the 1990s that destroyed much of Kabul.

Taliban spokesman Zabiullah Mujahid said they killed the foreigners because they were “spying for the Americans” and “preaching Christianity.” In a Pashto language statemen, the Taliban also said the team was carrying Dari language bibles and “spying gadgets.”

Frans said the International Assistance Mission, or IAM, one of the longest serving non-governmental organizations operating in Afghanistan, is registered as a nonprofit Christian organization but does not proselytize.

Frans said the team had driven to Nuristan, left their vehicles and hiked for nearly a half day with pack horses over mountainous terrain to reach the Parun valley, where they traveled from village to village on foot offering medical care for about two weeks.

“This tragedy negatively impacts our ability to continue serving the Afghan people as IAM has been doing since 1966,” the charity said in a statement. “We hope it will not stop our work that benefits over a quarter of a million Afghans each year.”

Among the dead was team leader Tom Little, an optometrist from Delmar, N.Y., who had been working in Afghanistan for about 30 years and spoke fluent Dari, one of the two main Afghan languages, Frans said. Little, along with employees from other Christian organizations, were expelled by the Taliban government in August 2001 after the arrest of eight Christian aid workers — two Americans and six Germans — for allegedly trying to convert Afghans to Christianity.

He returned to Afghanistan after the Taliban government was toppled in November 2001 by U.S.-backed forces. Known in Kabul as “Mr. Tom,” Little supervised a network of IAM eye hospitals and clinics around the country largely funded through private donations.

“He was a remarkable man, and very committed to helping the people of Afghanistan,” said David Evans of the Loudonville Community Church in New York.

Little had been making such trips to Afghan villages for decades, offering vision care and surgical services in regions where medical services of any type are scarce.

The work has long been fraught with risk, but Evans said Little was a natural for the job. He spoke the language, knew the local customs, and had the patience and diplomatic skills to handle sticky situations.

Another relief organization, Bridge Afghanistan, said on its website that the group included one of its members, Dr. Karen Woo, who gave up a job in a private clinic in London to do humanitarian work in Afghanistan.

In a fundraising blog posted last month, Woo said the mission to Nuristan would require hiking with pack horses through mountains rising to 16,000 feet to reach the Parun valley, a harsh, isolated area about 9,500 feet above sea level where an estimated 50,000 people eke out a primitive existence as shepherds and subsistence farmers.

“The expedition will require a lot of physical and mental resolve and will not be without risk but ultimately, I believe that the provision of medical treatment is of fundamental importance and that the effort is worth it in order to assist those that need it most,” she wrote.