Story highlights Polio workers shot dead on Sunday in northwest Pakistan 
 
 Female suicide bomber attacks bus with women on it, source tells CNN 
 
 Pakistani official thinks "homegrown terrorists" may be responsible 
 
 Officer dies in bombing of Pakistan founder's home 
 
 Militants, including a female suicide bomber, attacked a university bus carrying women in southwestern Pakistan and then struck a hospital where the survivors were taken for treatment, authorities said Saturday. 
 
 The militants laid siege to the Bolan medical complex in Quetta, holding hundreds of patients, physicians and nurses hostage as they battled security forces, authorities said. 
 
 An intelligence official, who requested anonymity since he was not authorized to speak to media, told CNN a female suicide bomber carried out the bus attack. 
 
 Twenty-eight people, including four militants, were killed in the siege at the hospital. The gunmen killed four security force members, a medical administrator, and the deputy commissioner of Quetta. Four nurses died in the crossfire, police said. Two militants blew themselves up, and two more died in a shootout, authorities said. 
 
 Among the hospital patients were more than 20 people wounded in the university bus explosion, which killed at least 14 women, Interior Minister Chaudhry Nisar Ali Khan said. 
 
 Several others were wounded in another blast tphat struck near the hospital's emergency room as the bus bombing victims were rushed in. 
 
 Photos: Photos: Bus bomb, hostages in Pakistan Photos: Photos: Bus bomb, hostages in Pakistan Bus bomb, hostage situation in Pakistan – Pakistani paramilitary soldiers take positions after militants attacked a hospital in Quetta, Pakistan, on Saturday, June 15. Several militants held hundreds of people hostage inside the Bolan medical complex. Hide Caption 1 of 9 Photos: Photos: Bus bomb, hostages in Pakistan Bus bomb, hostage situation in Pakistan – Pakistani soldiers arrest a suspected militant at the hospital. Among the patients at the complex were people wounded in a bus bombing near Sardar Bahadur Khan Women University that killed 12 female students. Hide Caption 2 of 9 Photos: Photos: Bus bomb, hostages in Pakistan Bus bomb, hostage situation in Pakistan – A man carries an injured boy after the hospital attack. Seven people have killed in the siege of the hospital. Hide Caption 3 of 9 Photos: Photos: Bus bomb, hostages in Pakistan Bus bomb, hostage situation in Pakistan – Soldiers take position near the hospital. Hide Caption 4 of 9 Photos: Photos: Bus bomb, hostages in Pakistan Bus bomb, hostage situation in Pakistan – A man carries an injured boy away from the scene. Hide Caption 5 of 9 Photos: Photos: Bus bomb, hostages in Pakistan Bus bomb, hostage situation in Pakistan – Soldiers shift an injured colleague into a van. Hide Caption 6 of 9 Photos: Photos: Bus bomb, hostages in Pakistan Bus bomb, hostage situation in Pakistan – People exit the hospital in Quetta. Hide Caption 7 of 9 Photos: Photos: Bus bomb, hostages in Pakistan Bus bomb, hostage situation in Pakistan – Firefighters extinguish a burning university bus after the bomb blast in Quetta. Hide Caption 8 of 9 Photos: Photos: Bus bomb, hostages in Pakistan Bus bomb, hostage situation in Pakistan – Firefighters work to extinguish the burning bus. "All the (bus) victims are women teachers and students," according to a police official, Mir Zubair Mehmood, in Quetta. Hide Caption 9 of 9 
 
 "All the (bus) victims are women teachers and students," said Mir Zubair Mehmood, a police official in Quetta. The blast shattered the windows of offices and classrooms inside Sardar Bahadur Khan Women University. 
 
 The university bus was parked at the school on the outskirts of Quetta, the capital of Balochistan province in southwestern Pakistan. 
 
 There was no immediate claim of responsibility. But Pervez Rasheed, the country's information minister, said, "We do not think there is any foreign involvement in these attacks -- this looks like homegrown terrorists." 
 
 U.N. Secretary-General Ban Ki-moon condemned the attacks, saying "violence against women and educators has increased in recent years. The aim being to keep girls from attaining a basic right to education." 
 
 Ban called on Pakistan's new leader, Nawaz Sharif, to do "all possible to bring the perpetrators to justice." 
 
 On Sunday, gunmen killed two polio workers who were making home visits in Khyber Pakhtunkhwa province in northwestern Pakistan, police said. Sharif called the attack "cowardly and inhumane." 
 
 The attack occurred in Ziarat, one of the country's top tourist spots, about 150 kilometers (93 miles) from Quetta. Jinnah spent the last days of his life at the home. 
 
 Islamabad summons a top U.S. envoy over deadly zone strike 

 Image copyright AFP 
 
 The women's university at the centre of Saturday's deadly twin attacks in the Pakistani city of Quetta has been shut down until further notice. 
 
 In the first incident a bomb on a university bus killed 14 women. Gunmen then killed 11 when they laid siege to the hospital treating the wounded. 
 
 Sardar Bahadur Khan University is the only all-female university in troubled Balochistan province. 
 
 The move is seen as a safety precaution in a city which has seen many attacks. 
 
 The site of the five-hour gun battle that unfolded after the bus bombing, the sprawling Bolan Medical Complex in Quetta, has also been closed indefinitely. 
 
 Lashkar-e-Jhangvi Founded in the 1980s, Lashkar-e-Jhangvi is a Sunni Muslim militant group blamed for a string of sectarian and high-profile terror attacks 
 
 Banned in Pakistan in 2001 and designated a terrorist group by the US in 2003 
 
 The group has ties to other militant networks such as the Pakistani Taliban 
 
 It regularly attacks Shia targets, but has also been linked to major attacks such as the 2007 assassination of former PM Benazir Bhutto Profile: Lashkar-e-Jhangvi 
 
 An extremist Sunni group, Lashkar-e-Jhangvi, has said it carried out both attacks. A spokesperson for the group said a female suicide bomber had been used to target the university students. 
 
 Although police now say they have found the severed head of a woman from the scene, they say the investigation is continuing to see if this really was a suicide attack. 
 
 Correspondents say that the use of women as suicide bombers in Pakistan has been rare. 
 
 On Sunday, Quetta observed an official day of mourning but Monday saw yet more groups, such as the Balochistan Bar Association, declare a strike to mourn the attacks. 
 
 Saturday's bloodshed began when a bomb exploded on a bus carrying students at Sardar Bahadur Khan Women's University. 
 
 When survivors were brought to the medical centre, militants stormed the building and started shooting indiscriminately. 
 
 The battle between the militants and security forces left nurses, security personnel and a senior city official among the dead. 
 
 Four attackers were also killed and one arrested, officials say. 
 
 Quetta, a city of 900,000 people in the south-west of the country, has long been troubled by violence mainly targeting the Shia Muslim minority, often claimed by groups such as Laskar-e-Jhangvi. 
 
 In January at least 81 people, mainly Shia Muslims, were killed in a bomb attack on a snooker hall in the city. And in February almost 90 died when a bomb ripped through a marketplace in a Hazara Shia part of the city.
– A women's university in Pakistan has closed indefinitely after a pair of outrageous terror attacks this weekend. First, militants bombed a university bus in Quetta on Saturday, killing 14 women. They then went to the hospital where the survivors were taken and began, in the words of the BBC, "shooting indiscriminately," setting off a five-hour siege. That attack saw 28 more killed, including four gunmen, CNN reports, though other outlets have lower counts. The hospital has also closed indefinitely. The initial bus bombing was reportedly carried out by a female suicide bomber—a rarity in Pakistan. The Sunni militant group Lashkar-e-Jhangvi has claimed responsibility for the attacks. Al-Jazeera notes that Sardar Bahadur Khan Women's University was the only school in the southwestern province of Balochistan dedicated to solely educating women.