At least one civilian and four suicide bombers have been killed after gunmen attacked Peshawar's Christian Colony this morning and exchanged fire with security forces, security sources said.

Director General Inter-Services Public Relations Asim Bajwa confirmed on Twitter "all four suicide bombers were killed" and a clearance operation is underway.

Firing reportedly began around 6:00 am, when gunmen, wearing suicide jackets, attacked the colony, the sources said.

Two attackers detonated their suicide jackets while two others were killed by security forces, the sources said.

Four suicide bombers, who were also equipped with arms and ammunition, entered the neighborhood after attacking a security guard in the early morning, Peshawar Police Superintendent Kashif Zulfikar told CNN. "We have enhanced the security of Christians establishments, schools, hospitals, colonies and churches," said Zulfikar. The official said the attackers might have been attempting to enter an adjacent security installation by exploiting weaker security arrangements in the residential area.

A Pakistani Taliban splinter group claimed responsibility for both attacks in an emailed statement. "If Islamic law is not imposed across the country, such attacks will continue to be carried out," the statement said. The Islamist group, which briefly declared allegiance to Middle East-based Islamic State in 2014 but recently said it was no longer affiliated with them, also staged the Easter Day attack on Christians in a park in Lahore that killed 72 people including at least 29 children.

Pakistan Prime Minister Nawaz Sharif condemned the attacks in a statement released by his office.

"These cowardly attacks can not shatter our unflinching resolve in our war against terrorism," he said. "These receding elements are showing frustration by attacking our soft targets. They shall not get space to hide in Pakistan."

Punjab Law Minister Rana Sana Ullah has presented a resolution in the Punjab Assembly of condemning the attack on Christian Colony.

In the light of the attack, Christian colonies and Churches are put on high alert in Sindh. 

The city suffered its worst terror attack in December 2014 when Taliban gunmen massacred more than 150 children and staff, at the Army Public School.

Recently, however, there had been a lull in violence. In March, a bomb blast killed 15 government employees traveling in a bus.

The attack on the Christian Colony comes barely a day after Director-General (DG) Inter-Services Public Relations (ISPR) Asim Bajwa gave an exhaustive rundown of progress made against militants in the country's northwestern region in Operation Zarb-i-Azb which was launched in June 2014.

He highlighted that Pakistan had suffered a cumulative loss of $106.98 billion in the war on terror between 2001 and 2015.

“We are not doing it for anyone but ourselves,” he stressed.

He said 3,500 terrorists had been eliminated during the course of Operation Zarb-i-Azb, while 2,272 soldiers were and 537 personnel had embraced martyrdom, including 18 officers, 35 junior commissioned officers and 484 soldiers.