Gunmen pulled 20 Shiite Muslims from a bus and killed them at point blank range in Pakistan on Thursday, the third such incident in six months, officials said.
The incident happened in the northwestern district of Mansehra as the bus was travelling between Rawalpindi, the headquarters of the Pakistani army, and the mainly Shiite northern city of Gilgit.
Officials said it was ambushed in the hills of Babusar Top, around 100 miles (160 kilometres) north of the capital Islamabad, although they differed over details of the incident.
"Ten to 12 people wearing army uniform stopped the bus and forced some people off the bus," said Khalid Omarzai, administration chief in Mansehra.
"After checking their papers, they opened fire and at least 20 people are reported to have been killed. This is initial information and the final toll may go up. They are all Shiites," he said.
Local police official said that the gunmen were masked, but the victims were pulled from three separate vehicles in the district, which neighbours the Swat valley, a former Taliban stronghold.
"They stopped three vehicles, searched them and picked up people in three batches of five, six and nine and shot them dead. They were all Shiites," he said.
Sectarian violence linked to Gilgit, a popular tourist destination for wealthy Pakistanis and expatriates who live in the country, has increased in recent months.
It is the capital of Pakistan's far northern Gilgit-Baltistan region and is popular with mountaineers as a gateway to the Karakoram and Himalayan mountain ranges.
On February 28, gunmen in military fatigues hauled 18 Shiite Muslim men off buses travelling from Rawalpindi to Gilgit in the northern district of Kohistan, shooting them dead in cold blood.
On April 3, a Sunni Muslim mob dragged nine Shiite Muslims from buses and also shot them dead in the town of Chilas, about 60 miles south of Gilgit.
Human rights groups have heavily criticised Pakistan for failing to crack down on sectarian violence between the country's majority Sunni and minority Shiite communities that has killed thousands.