A Pakistani cleric known as the “father of the Taliban” was stabbed and shot to death in his home outside Islamabad on Friday, his family and aides said.

The killing of Maulana Sami ul-Haq, 82, by unknown assailants came amid a spate of violent nationwide protests by Muslim groups angered at a ruling by Pakistan’s Supreme Court on Wednesday that acquitted a Christian woman on charges of blasphemy.

It was not immediately clear whether the slaying was related to the ongoing unrest. But aides to Haq said he had attempted to join the protests after weekly prayer services. He had returned home because roads were blocked.

Angry protesters were seen on videos posted on social media smashing and burning cars on the highway between Islamabad and Rawalpindi.

Haq, a former senator, was the longtime leader of a conservative Sunni Muslim party that preached opposition to the West. For several decades, he ran a seminary in Peshawar near the Afghan border that trained hundreds of young men to join the Taliban forces in Afghanistan in the 1990s.

As news spread of the attack, Pakistani officials and religious leaders expressed shock and sorrow at his death.

“I have great respect for Maulana Sami, and his death is a huge loss to Pakistan,” said Maulana Fazl-Ur Rehman, a leading Sunni religious politician who heads another conservative Sunni party.

Pakistan’s interior minister, Shehyar Afridi, condemned the slaying in a statement and said he “shared the pain” of his family. He said Haq’s religious and political service to the country would be long remembered.

The news also brought a fresh outbreak of demonstrations on the darkened streets of Islamabad, where protests against the acquittal of Asia Bibi by the high court had erupted Friday, as well as in other cities, for the third day in a row. At 8 p.m., officials of the federal capital asked residents in an online post to stay home due to the assassination.