Gunmen have opened fire on a bus carrying members of the minority Ismaili sect in Pakistan's southern port city of Karachi, killing at least 43 people in an attack that drew swift condemnation from the Pakistani government, India, and the Aga Khan, the spiritual leader of the Ismaili community.
Authorities said the attackers first fired at the bus from outside, then entered the vehicle and began shooting survivors in the head.
Provincial police chief Ghulam Haider Jamali said the passengers were en route to a community center for Ismaili Shi'ite Muslims when at least six gunmen stopped the bus and began killing the passengers.
He said 16 women and 27 men were killed, and more than a dozen people were wounded, before the gunmen fled on three motorcycles after the May 13 attack.
Reports said some young children survived by hiding under the bodies of the dead.
Television channels carried pictures of a pink bus riddled with bullet holes while ambulances lined up nearby to take away the wounded and the dead
Security forces were deployed outside two hospitals in Karachi where the wounded were taken for treatment.
Karachi police spokesman Atiq Sheikh told RFE/RL that the gunmen left behind a pamphlet announcing that the attack was "revenge for the killing in Syria and Iraq."
The pamphlets were headlined Advent Of The Islamic State and used derogatory Arabic to describe Shi'a.
The pamphlets also blamed Shi'a for "barbaric atrocities...in the Levant, Iraq, and Yemen."
A splinter group of the Pakistani Taliban called Jundullah claimed responsibility for the attack, which was quickly condemned by Pakistani political leaders as well as India's prime minister.
A spokesman for Jundullah, Ahmed Marwat, told RFE/RL that the group will continue to carry out attacks against Shi'a, including Ismailis, and Christians.
The Al-Qaeda-affiliated militant group has targeted Shi'a and foreign tourists in the past. It pledged loyalty to Islamic State (IS) militants in November 2014.
Ismailis are followers of Prince Shah Karim al-Husseini Aga Khan, a globally known philanthropist and business leader who claims to be the 49th hereditary imam of the Shi'ite Imami Ismaili Muslims.
"This attack represents a senseless act of violence against a peaceful community. My thoughts and prayers are with the victims and the families of those killed and wounded in the attack," the Aga Khan said a statement posted on the Aga Khan Development Network website.
Sectarian Attacks Increase
Attacks on Shi'a have been increasing in recent years in Karachi as well as in Quetta, the northwestern area of Parachinar, and the far northeastern town of Gilgit.
About 1,000 Shi'a have been killed in sectarian attacks in majority-Sunni Pakistan during the last two years.
Many of the previous attacks have been claimed by the hard-line Sunni group Lashkar-e Jhangvi, which views Shi'a as heretics.
The May 13 massacre was the worst attack against Shi'a in Pakistan since January 30, when a suicide bomber attacked a mosque in the southern district of Shikarpur, killing 61.
Prime Minister Nawaz Sharif called for an investigation and extended condolences to relatives of the dead.
Sharif described the attack as "a deplorable attempt to spread chaos in Pakistan and a condemnable attempt to make people fight against each other" from different communities.
The chief minister of Sindh Province, whose capital is Karachi, ordered the immediate suspension of local police commanders in the area.
Chief Minister Syed Qaim Ali Shah said the authorities were trying to determine whether a security force had been assigned to protect the bus, or whether the Ismaili community had asked for protection.
In Karachi, followers of the Ismaili faith live in walled compounds and travel only in convoys due to security threats made against them by militant Sunni extremists.
Pakistan's Ismaili community is settled in some Himalayan valleys in the northern part of the country as well as in Karachi.
Imran Khan, leader of the opposition Pakistan Tehrik-e Insaf party, said the killings raise questions about the provincial government's performance.
In a statement, Khan said he was "stunned and grieved at [the] most condemnable terror attack in Karachi against "a most peaceful community."
Altaf Hussain, the leader of the Muttahida Qaumi Movement (MQM), called the killings "the worst form of terrorism" and said "those behind the attack are savages.
Indian Prime Minister Narendra Modi also condemned the attack, saying, "we stand firmly with the people of Pakistan in this hour of grief."
With reporting by Reuters, AP, AFP, and Dawn.com