Thousands of hardline Muslim activists filled the streets of the Pakistani capital Islamabad, demonstrating in support of the nation's severe anti-blasphemy laws.
Police fired tear gas at the protesters, who had gathered about 700 meters from the parliament building in Islamabad, setting fires and clashing with security forces.
Protesters rallied in the memory of Mumtaz Qadri, a former Pakistani policeman who assassinated the governor of Punjab province Salman Taseer. Qadri was in Taseer's bodyguard detail when he killed him in early 2011. He was executed on February 29.
Qadri shot the governor 28 times due to his outspoken stance against Pakistan's harsh blasphemy laws, which mandate the death penalty for anyone who says anything offensive to the Prophet Mohammed.
More than 60 people, the majority of them police officers, were injured in the clashes on Sunday, hospital officials told Reuters.
Last year, 210 cases of criminal blasphemy were filed. Critics say many cases are leveled against Christians and other religious minorities and are often used to exact revenge or seek advantage in personal or business disputes, Reuters reports.
As of now, the state has not carried out capital punishment in any of the cases, but extremist Pakistanis have been known take the law into their own hands.
At least 65 people, including lawyers, defendants and judges, have been murdered over blasphemy allegations since 1990, according to figures from a Center for Research and Security Studies report and local media.
The protests come at a time when Pakistan's civil government has been attempting to crack down on extremism.
Earlier today, a bomber blew themselves up in the parking area of Gulshan-e-Iqbal Park, just outside the exit gate and a few meters away from children's swings. The attack is seen as targeting Pakistan's Christian minority, who were partaking in Easter celebrations.
At least 65 were killed, mostly women and children.