At least 43 members of Pakistan's Shiite Ismaili minority were killed when gunmen opened fire on their bus in Karachi on Wednesday, police said, with a leaflet at the scene claiming the attack on behalf of the Islamic State of Iraq and al-Sham. It was the second deadliest militant attack in Pakistan this year after 62 Shiites were killed in a suicide bombing in late January. Pakistan has seen a rising tide of sectarian violence in recent years, particularly against Shiites, who make up around 20 percent of the country's predominantly Muslim population of 200 million.