Islamabad, Pakistan (CNN) -- Choir members and children attending Sunday school were among 81 people killed in a suicide bombing at a Protestant church in northwest Pakistan.
It was one of the deadliest attacks ever on the Christian community in Pakistan.
The attack took place at the All Saints Church of Pakistan, in the violence-plagued city of Peshawar, about 120 kilometers (75 miles) from the country's capital, Islamabad.
A congregation of about 500 people was attending the church. Two attackers struck right as services concluded.
"Suicide bombers entered the church compound from the main gate and blew themselves up in the midst of the people," a statement posted on the diocese website read.
The outside of the church was peppered with debris. Crowds of men and rescue officials were covered in blood.
The attack left 120 people wounded, with 10 of them in critical condition, Dr. Arshad Javed, chief executive of Peshawar's Lady Reading Hospital, said Monday.
The Rev Humphrey S. Peters, Bishop of Peshawar, expressed condolences and called for prayers, but he also struck a defiant tone. In a statement, Peters condemned the local government, calling the attack a "total failure" of official efforts to protect minorities.
His criticism was echoed by hundreds of people who took to the streets in largely Christian areas of Pakistan, calling for better protection of minority groups.
The All Saints Church was built in 1883 inside the old walled city of Peshawar. It was built to resemble a mosque from the outside, not for security reasons but to symbolize unity.
Christians make up less than 3% of the population in the South Asian nation of 193 million. Militant groups have also targeted other minorities including Shiite Muslims, who are significantly outnumbered by Sunnis in Pakistan.
Attack claimed by Taliban offshoot
A splinter group of the Pakistani Taliban claimed responsibility for the church attack, blaming the U.S. program of drone strikes in tribal areas of Pakistan.
"Until and unless drone strikes are stopped, we will continue to strike wherever we will find an opportunity against non-Muslims," said Ahmed Marwat, a spokesman for TTP-Jandullah.
The main Pakistani Taliban, known as Tehrik-e-Taliban Pakistan (TTP), distanced itself from the attack.
"We refuse to take responsibility for the church blast. This is an attempt to sabotage peace talks between the TTP and the government," said spokesman Shahidullah Shahid.
Earlier this month, Pakistani officials announced plans to pursue peace talks with Taliban militants and withdraw troops from parts of the volatile northwestern region, which borders Afghanistan.
Prime Minister Nawaz Sharif on Sunday condemned the church attack and in a statement said he was praying for the recovery of those injured. Sharif said terrorists have "no religion" and that targeting innocents is against Islam.
But Khyber Pakhtunkhwa, of which Peshawar is the capital, is rife with Islamic extremists and has been the site of clashes between Pakistani security forces and militants.
Earlier this month, a roadside bomb in the province killed a top Pakistani general, just a day after the announcement of the plans for peace talks.
Journalists Sophia Saifi and Zahir Shah Sherazi contributed to this report.