Gunmen kill 43 in Karachi bus attack

At least 43 people have been killed and 20 injured in a gun attack on a bus carrying Ismaili Shia Muslims in the Pakistani city of Karachi, police say.

A police official said six gunmen on motorcycles had stopped the bus and fired indiscriminately at passengers.

Prime Minister Muhammad Nawaz Sharif has condemned the attack and ordered an investigation.

A splinter group of the Pakistani Taliban called Jundullah has said it carried out the attack.

'Dressed as police'

A leaflet was also left at the scene claiming the so-called Islamic State group was responsible.

It is the second deadliest militant attack in Pakistan this year after 62 Shia Muslims were killed in a suicide bombing in January.

About 60 people were on board the bus when it was stopped in the Safoora Goth area on its way to an Ismaili Shia place of worship, police said.

They said 9mm pistols were used.

The BBC's Urdu service editor Aamer Ahmed Khan said it seemed to be a well-planned attack.

He said the bus was making one of five daily scheduled trips between a gated community housing mainly Ismailis on the north-eastern outskirts and the main city.

The relatives of victims said as it was about to enter the city it was stopped by four men dressed as policeman who clearly intended to kill and fled minutes after the assault.

They said the bus driver was killed and an injured passenger drove it to Memon Hospital Institute.

One man at the hospital told AFP news agency: "I have come to collect the body of my young son. He was a student preparing for his first year exams at college."

In the violence by Taliban and Sunni militants against Shia Muslims in Pakistan in recent years, the Ismailis - who make up a tiny proportion of Shias - have been largely spared.

The BBC's Shahzeb Jillani in Pakistan says it is one of the biggest, if not the biggest, attack on the Ismaili community and has come as a major shock.

He described it as a progressive, educated, peaceful community.

A Jundullah spokesman said it carried out the attack because it considered the victims "kafir" or non-Muslim.

He threatened more attacks in the coming days against Ismailis, Shias and Christians.

Pakistan's Army chief Gen Raheel Sharif has cancelled a scheduled three-day trip to Sri Lanka and is personally leading the investigations into the attack, the BBC's Urdu editor said.

Who are the Ismailis?

Ismaili Shias, in common with other Shia Muslims, revere Ali, son-in-law of the Prophet Mohammed, but they also revere the Imam Ismail who died in 765 AD

They interpret the Koran symbolically and allegorically

They live in over 25 different countries

Their spiritual leader Prince Karim Aga Khan is a philanthropist and business magnate. He gives his name to bodies including a university, a foundation, and the Aga Khan Program for Islamic Architecture at Harvard University and the Massachusetts Institute of Technology

He has encouraged Ismailis settled in the industrialised world to contribute to those communities

Pakistan is about 20% Shia and 70% Sunni. Recent attacks on Shias in Pakistan include:

- In January, an attack on a Shia mosque in the southern province of Sindh killed 60 people

- In February, 20 people were killed in an attack on a Shia mosque in Peshawar

- Suicide bombings outside two churches in Lahore in March killed 14 people and wounded nearly 80; days later, a bomb after Friday prayers wounded 12 outside a minority Bohra mosque in Karachi.

Karachi, Pakistan's commercial capital of about 20 million people, has long had a reputation for sectarian violence.