Last Updated Jan 21, 2014 6:10 AM EST
KABUL -- Unknown gunmen on Tuesday seized and briefly held about 60 Afghan workers who were about to begin clearing Soviet-era anti-tank mines in western Herat province, the largest mass kidnapping undertaken in an economically important area now beset by security problems.
Halo's country director Farid Hamayun in Kabul confirmed to CBS News that all 63 workers who were kidnapped as they left their camp Tuesday morning had been freed -- most of them rescued in an operation by Afghan police.
None of the mine clearers were injured in the ordeal.
Hamayun and a Halo official at the group's headquarters in Scotland said nine of the Afghan workers managed to escape or were set free early on, and the rest were freed from their captors by police.
Herat, which borders Iran, has long been plagued by kidnappings. But a sharp downturn in security in the traditionally safe province would be a worrying sign ahead of the departure of most foreign forces by the end of this year.
There has been no claim of responsibility for the mass kidnapping.
The 60 Afghans working for the Halo Trust had arrived at a village in Pashtun Zarghun district before 8 a.m. to begin clearing anti-tank mines left over from the 10-year Soviet occupation of the 1980s.
"When they arrived, armed people on motorbikes came and forced them to get into their vehicles and made them drive to a nearby village," The Halo Trust's country director, Farid Homayoun, said.
The kidnappers forced the deminers out of the cars and marched them toward nearby mountains. They have not been seen since.
"Some deminers were able to escape but 60 staff are still with those people and at the moment the local shura are in negotiation for their release," Hamayun said earlier, using the Afghan word for elders.
Valon Kumnova, at Halo's office in the U.K., said the organization -- brought to fame in the 1980s by the late Princess Diana -- has some 3,000 staffers across Afghanistan, all of whom are Afghans hired and trained by the organization, with the exception of three international employees. Hamayun said Halo has been doing work in Herat since 2006 and has about 550 workers in that province alone.
A small group of deminers was held for a week by Taliban fighters in more volatile southern Kandahar district in April last year before being released.
In Herat, a commercial hub, kidnappers have generally targeted rich business people or their families, with residents staging strikes and protests to draw attention to the issue.
Bombings and insurgent attacks had been infrequent in Herat until recently, but security has deteriorated sharply in recent months. Residents told Reuters it had become dangerous to travel through districts bordering the provinces of Farah and Baghdis.