Pakistan’s Ismaili Shiite community is reeling from an attack Wednesday by gunmen that left at least 46 members of the religious minority dead in Karachi. The violence is the first of its kind directed at the community amid escalating militant threats against the predominantly Sunni Muslim country’s religious minorities, and was condemned by leaders including the Ismaili spiritual head, the Aga Khan.

The Aga Khan expressed his shock and sadness about the attack on Wednesday, condemning it as a “senseless act of violence against a peaceful community.” The attack was claimed by a splinter group of the Pakistani Taliban known as Jundallah, which pledged allegiance to the Islamic State late last year.

"These killed people were Ismaili, and we consider them kafir (non-Muslim),” Jundallah spokesman Ahmed Marwat told Reuters. Gunmen on motorcycles reportedly boarded a commuter bus carrying around 60 Ismailis and, according to witness accounts, fired indiscriminately into the crowd.

Pakistan’s Prime Minister Nawaz Sharif has also condemned the violence, drawing attention to the contributions of the Ismaili minority. "This is a very patriotic and peaceful people who have always worked for the well-being of Pakistan," he said.

The estimated 15 million-strong Ismaili Muslim community is a subset of Shiism, one of the two major branches of Islam. Ismailis live in more than 25 different countries, primarily in South and Central Asian nations like Pakistan, Afghanistan and Iran, though there are also significant communities in the United States, Canada and Britain.

Like other Shiites, Ismailis revere the Prophet Muhammad’s son-in-law Ali as his rightful successor but they follow a line of religious leaders from Imam Ismail in the eighth century. The current Aga Khan, Prince Karim Aga Khan, is believed to be a direct descendant of the prophet and is the 49th imam in the Ismaili succession. The Aga Khan is also well known as a philanthropist and business magnate with an estimated net worth of $800 million.

The Ismaili leader’s generous contribution of development funding to the Pakistani government means the Karachi attack is likely to cause some diplomatic tensions for Pakistan’s leaders, according to the BBC. Both the prime minister and the army chief have set aside other commitments to head to Karachi. 

While Ismailis make up a small proportion of the worldwide Muslim population, they have distinguished themselves by developing social welfare programs, including building of educational institutions in their communities of residence. Despite the community’s apolitical stance, it has nonetheless been subject to turmoil in the countries they’ve resided in, including in Uganda, where they were expelled along with other South Asians in the 1970s by dictator Idi Amin. The Aga Khan played an instrumental role in resettling the community.