Dozens killed as armed men open fire on bus in Pakistan

At least 43 people have been killed and more wounded in a gun attack on a bus in the Pakistani city of Karachi.

The bus belonged to the Ismaili Shia Muslim sect, and was targeted by gunmen at the Safoora Chowk intersection in the eastern part of Pakistan's largest city on Wednesday.

The assault is Pakistan's deadliest in months. Provincial police chief Ghulam Haider Jamali said 43 people were killed, including 16 women, and another 13 people were wounded.

Jamali added that six attackers are believed to have been involved, and the gunmen approached the bus on three motorcycles.

Testimony from those who have seen the bus, and footage of it, suggests that the attackers boarded the bus and shot indiscriminately while inside.

Jamali said that those killed had been hit by 9mm gunfire, indicating that handguns may have been used in the attack.

Pamphlets left at the scene of the attack claimed that it had been carried out by fighters allied to the Islamic State of Iraq and the Levant (ISIL) armed group.

“Oh soldiers of the [unbelievers]! We swear that we will make you and your families cry tears of blood and will not rest until we have cleansed this land of you and established Shariah,” read the pamphlet.

Jundullah, a Pakistani armed group that pledged allegiance to ISIL in November last year, also claimed responsibility for Wednesday's attack.

Following the attack, the bus was driven to the nearby Memon Medical Institute and Hospital with 62 people still inside — many of whom had already died.

“When the bus came into the hospital, there were some people whose heads were hanging limply out of the windows,” said a hospital official, on condition of anonymity.

Many of those injured were in critical condition, hospital official Salma Wahid told Al Jazeera.

“Their condition is serious and they were covered in blood when they came in,” said Wahid, adding that many were unconscious when they were admitted.

Sindh Chief Minister Qaim Ali Shah, who heads the provincial government, said that he had ordered senior police officials to investigate the incident.

“I have taken it very seriously. I am terribly sorry that this nasty incident has taken place. Whoever it is, we have to detect the offense and take action against the culprits,” he told local media shortly after the attack.

This is the fifth major attack against Shia Muslims in Pakistan this year, with previous attacks including suicide attacks and bombings at Shia mosques in Rawalpindi, Islamabad, Peshawar and Shikarpur. Those attacks claimed the lives of at least 98 people.

Karachi, home to at least 20 million people, has often seen incidents of targeted attacks on political, ethnic and sectarian grounds, although violence has decreased since a paramilitary operation against criminals was launched in September 2013.

Al Jazeera and wire services