Outbursts of sectarian violence occur regularly in Pakistan. Hard-liners from the Sunni majority who consider Shiites to be heretics have targeted the sect with bombs and shootings, with Shiite attacks on Sunnis less common, at least in recent years.
In the wake of Friday's clashes, residents of Rawalpindi, a city next to the capital that is home to a large military presence, were ordered to stay in their homes until further notice, said Shoaib Bin Aziz, the head of the information department of the government of Punjab province.