(A student shout slogans as he marches with others during a protest rally against an anti-Islam film made in the U.S. which they say mocks the Prophet Mohammad, in Gilgit September 19, 2012. Picture taken September 19, 2012. REUTERS/Akhtar Soomro )

About 20 men dressed as Pakistani soldiers boarded a bus bound for a Muslim festival outside this mountain town and checked the identification cards of the passengers. They singled out 19 Shi’ites, drew weapons and slaughtered them, most with a bullet to the head.

The shooters weren’t soldiers. They were a hit squad linked to the Sunni Muslim extremist group Lashkar-e-Jhangvi, or LeJ. They had trekked in along a high Himalayan pass that hot August morning to waylay a convoy of pilgrims.

Here and across Pakistan, violent Sunni radicals are on the march against the nation’s Shi’ite minority.

With a few hundred hard-core cadres, the highly secretive LeJ aims to trigger sectarian violence that would pave the way for a Sunni theocracy in U.S.-allied Pakistan, say Pakistan police and intelligence officials. Its immediate goal, they say, is to stoke the intense Sunni-Shi’ite violence that has pushed countries like Iraq close to civil war.