The violence worsened immediately after September 11 and the expulsion of the Taliban from Afghanistan. In 2002, 12 Shia Hazarapolice cadets were gunned down in Quetta. In 2003, the main Shia Friday Mosque was attacked in Quetta, killing 53 worshippers. March 2, 2004, at least 42 persons were killed and more than 100 wounded when a procession of the Shia Muslims was attacked by rival Sunni extremists at Liaquat Bazaar in Quetta.Separately, on October 7, 2004, a car bomb killed 40 members of an extremist Sunni organization in Multan. 300 people died during 2006.
However, since September 11, there has been an overall decline in violence, as Saudi sources are more reluctant to fund Sunni extremists in the wake of increased scrutiny of Saudi ties to hardline extremists.
On December 28, 2009, as many as 40 Shias were killed in an apparent suicide bombing in Karachi. The bomber attacked a Shiaprocession which was held to mark Ashoura. Since June 2010 in Karachi, Sipah-e-Sahaba is involved in the target killing of seven innocent bystanders and intellectuals; all were from the Twelver Shia Muslim community. Sectarian riots as well as target killing of doctors in the provincial capital have been sending alarm bells to the present democratic system. Karachi had witnessed similar sectarian tension in the early 1980s when then President Zia-ul-Haq was in power. The military regime of those years had been backing certain groups to strengthen its rule and Karachi underwent worst situation after the sectarian riots. The Shia-Sunni clashes had started from the same section of the city (i.e. Godra Colony in New Karachi) after a small incident, and subsequently the clashes gripped the entire city, that hasn't stopped yet and continues.
In early September 2010, three separate attacks were reported in different parts of Pakistan. The first one took place on September 1 in Lahore where at least 35 Shias were killed and 160 unknown people injured during a procession. The second one was reported to have taken place in Mardan on Ahmadiyyas in which at least one person was killed. The third attack also occurred on September 3 but in the city of Quetta which killed around 56 people during another procession calling for solidarity with Palestinians.
On December 16, a mortar attack killed nine (9) people, including women and children in Hangu, a town that has been a flash point for sectarian clashes between Shia and Sunni communities in Khyber Pakhtunkhwa (KP) Province, near tribal area. On the same day in another attack one child was killed and 28 people were wounded in Peshawar, the capital of KP province, as Shia Muslims marked Ashura.
According the my point of view Sipa-e-Saiba and polioticle parties like Jamat-e-Islami are the main reason behind these attacks. These banned parties supported by Taliban attack and kill people without any haste. Extremisim is panitrated in lives of typical Pakistanies, there is no tolrance left in Pakistanis. We can hope that Things will change in future where will be able to tolarate each other and live happyli side by side. Util now we are not going in right direction.