A Christian priest was shot dead and another wounded by unidentified gunmen who opened fire on them as they were returning home from Sunday mass in Pakistan's northwestern Peshawar city, police said, describing it as a "terrorist act".

Bishop William Siraj was shot multiple times and died on the spot, while Father Naeem Patrick was wounded in the attack that took place near Ring Road within Gulbahar police station limits, police said.

The police immediately rushed to the spot and started the search operation. A strict security has been made at the entry and exit points to nab the culprits.

No group has immediately claimed responsibility for the attack, the latest on Pakistan's small Christian minority that has often been targeted by militants in recent years.

Capital City Police Officer Abbas Ahsan said that there were two attackers involved in the attack.?

"A comprehensive investigation has been launched," he said, adding that it was a "terrorist act".

"We are determined to protect minorities," he said, adding that a team consisting of officials from the Counter Terrorism Department (CTD) and Peshawar police had been formed to probe the case.

Police said they were reviewing the CCTV footage to locate the attackers, who escaped on motorcycles.

"Evidence is being collected from the scene of the crime and CCTV cameras are also being checked," police said in a statement.

"William Siraj was a padre at a church within Chamkani police station limits," it said.

The body had been shifted to the hospital for conducting an autopsy while further investigation was underway, it added.

A spokesperson for Lady Reading Hospital said that the injured priest was discharged after being provided medical treatment for minor injuries.

Hafiz Muhammad Tahir Mahmood Ashrafi, Chairman Pakistan Ulema Council and Special Representative of the Prime Minister Imran Khan for Interfaith Harmony and Middle East, condemned the attack on the Christian priests.

Khyber Pakhtunkhwa Chief Minister Mehmud Khan has condemned the attack and directed the police to take necessary steps for arresting the attackers.

The perpetrators would not be able to escape the clutches of the law, he added.

Khan also ordered the best medicare facilities for the injured Father. The angry protestors blocked the ring road protesting killing of the bishop.

According to the 2017 census, Hindus constitute the largest religious minority in Pakistan. Christians make up the second largest religious minority.