At least six people, including four Pakistan army officials were killed and twenty others were injured in a suicide blast in Lahore on Wednesday.

A Taliban suicide bomber struck a vehicle carrying census workers in eastern Pakistan on Wednesday, killing two data collectors and four soldiers who were escorting them, officials said.

The attack took place on the outskirts of Lahore, said Malik Ahmad Khan, the provincial government spokesman. A local police official, Mohammad Afzal, said that 15 other people were wounded in the blast, which damaged nearby shops.

Mohammad Khurasani, a spokesman for the Pakistani Taliban, claimed responsibility for the attack, saying the group sought to target Pakistan's "impure army," which he called a "slave of America." The militant group's chief, Mullah Fazlullah, who is believed to be hiding in Afghanistan, ordered the attack, the spokesman said.

Elsewhere in Pakistan, two gunmen shot and killed a former Pakistani army colonel in the southern city of Karachi, said police official Rao Rafiq. Lashkar-e-Jhangvi, a Pakistani group linked to the Taliban and Al-Qaeda, claimed responsibility in a text message sent to an Associated Press reporter.

Since Pakistan threw its support behind the United States in its war against terror in 2001, militant groups have killed thousands of people in a bid to overthrow the government and install their own harsh interpretation of Islamic law.

According to a report on Geo TV, two vans and a motorcycle were damaged in the blast, which took place at 7.15 am. The report also added that a van and another vehicle was set ablaze after the blast.

Pakistan's military has carried out scores of operations, killing thousands of suspected militants.

Pakistan Army chief, General Qamar Javed Bajwa, paid tribute to the victims of Wednesday's attack and said the census would be completed at any cost.

Rana Sanaullah, a Cabinet member in the Punjab government, said such attacks are being planned and executed by militants in Afghanistan — an often repeated claim by Islamabad.

Kabul denies it is sheltering any militant groups, but various extremist factions launch attacks on both countries across the porous border.

Pakistan launched the national census last month, the country's first in 19 years.

Tens of thousands of data collectors, supported by 200,000 Pakistani soldiers, go door-to-door for the project, which is to be finished by 15 May. However, societal conservatism and a lack of women census takers could result in Pakistan's female population being under-represented.

The Punjab provincial government has condemned the attack and ordered a report on the blast.

. @CMShehbaz has strongly condemned the blast at Bedian Road. — Govt Of The Punjab (@GovtOfPunjab) April 5, 2017

.@CMShehbaz . @CMShehbaz has extended sympathy and condolences to the bereaved families. — Govt Of The Punjab (@GovtOfPunjab) April 5, 2017

.@CMShehbaz . @CMShehbaz has sought report of the blast at Bedian road. — Govt Of The Punjab (@GovtOfPunjab) April 5, 2017

Lahore had been on a security high alert for a while.

On 23 February, a blast in an upscale area in Lahore killed eight people and injured 30 people.

With inputs from agencies

