Gunmen kill 45 in a bus in Karachi (Third Lead)

At least 45 people were killed and 24 others injured when gunmen opened fire inside a bus carrying Ismaili Muslims, a sub-sect of the Shia community, in the Pakistani port city of Karachi on Wednesday.

Jundullha, a proscribed Al Qaeda-affiliated outfit, has claimed responsibility for the attack, Pakistani media reports said.

The incident took place near the city's Safoora Chowk area in the provincial capital of Sindh.

Sindh Police Inspector General Ghulam Haider Jamali said 60-65 people were travelling in the bus.

Hospital sources said the victims included 16 women. No children were on board.

"At least six gunmen attacked the bus in the Safoora Goth area of Karachi," said a senior police official.

"The gunmen stopped the bus and first fired at it from outside," said the policeman. "Then they entered inside the bus and opened fire indiscriminately. After that they checked to see if anyone was left uninjured."

Video footage of the bus did not show bullet holes on the body of the vehicle suggesting that the attackers entered the bus and fired their guns.

Jundullha, which started off from South Waziristan, has targetted Shia minorities and foreign tourists in the past as well. In November last year, the group had pledged its support to the Islamic State (IS) Sunni radical group.

In the past, Jundullah has claimed responsibility for several attacks including a blast near the Wagah border in November 2014 and the July 2013 attack on the compound of Pakistan's Inter Services Intelligence (ISI) in Sukkur. It has also claimed responsibility for several attacks on polio eradication workers across the country.

Meanwhile, Pakistan Prime Minister Nawaz Sharif condemned the attack and summoned a report from the interior ministry which later sought details of the attack from the IGP Sindh and the director general of the Pakistan Rangers.

Sharif also cancelled his official engagements for the day and left for the port city.

The attack has drawn widespread condemnation from both political and religious leaders.

Indian Prime Minister Narendra Modi has also condemned the incident.

"The attack in Karachi is deeply saddening & utterly condemnable. Our thoughts are with the families of the deceased," Modi tweeted.

"We stand firmly with the people of Pakistan in this hour of grief. I wish all those injured quick recovery," he added.

Pakistan Tehreek-e-Insaf (PTI) chief Imran Khan tweeted that he was stunned and grieved at the most condemnable terror attack in Karachi on ordinary citizens of Pakistan belonging to a most peaceful community.

The attack was also condemned by Pakistan President Mamnoon Hussain and Chief Minister of Sindh Syed Qaim Ali Shah. Chief of Army Staff General Raheel Sharif canceled a pre-scheduled three-day visit to Sri Lanka.

The Sindh chief minister has ordered the immediate suspension of the area's station house officer and district superintendent of police.