Islamic State militants kill 43 Shia Ismaili Muslims in Karachi

Police cordon off the site of an attack by gunmen in Karachi, Pakistan, Wednesday, May 13, 2015. (Source: AP)

A Pakistani security official displays cartridges he collected from the scene of an attack on a bus, in Karachi, Pakistan, Wednesday, May 13, 2015. (Source: AP)

Pakistani paramilitary troops stand guard outside a local hospital following an attack on a bus in Karachi, Pakistan, Wednesday, May 13, 2015. (Source: AP)

The attack came a day after Prime Minister Nawaz Sharif visited Kabul and declared that enemies of Afghanistan are also enemies of Pakistan. (Source: AP)

People visit a local hospital following an attack on a bus in Karachi, Pakistan, Wednesday, May 13, 2015. (Source: AP)

Ambulances take bodies of attack victims to a hospital for autopsies in Karachi, Pakistan, Wednesday, May 13, 2015. (Source: AP)