Islamabad, Pakistan - A suicide bombing targeted a Pakistani government census team, killing at least six people in the eastern city of Lahore, officials say.

The blast on Wednesday morning in Pakistan's second largest city also wounded at least 18 people, many with serious injuries.

According to a police report, two attackers on a motorcycle approached a van carrying the census team. One attacker disembarked and exploded his suicide vest as the other sped away. The dead included four military personnel and two civilians.

The Tehreek-e-Taliban Pakistan group claimed responsibility, saying it was a suicide attack.

"The target seems to be the census team and the soldiers guarding them," Malik Ahmed Khan, a spokesperson for the Punjab government, told local television news channel Geo.

'Act of terrorism'

Rana Sanaullah, a senior provincial minister, told Geo the attack "appeared to be an act of terrorism".

"Sacrifice of precious lives of civil enumerators and soldiers is beyond any doubt a great sacrifice," Qamar Javed Bajwa, Pakistan's army chief, said in a statement, without giving any details about the number of soldiers killed in the bombing.

"Conduct of census will be completed at any cost."

Pakistan's Bureau of Statistics launched its first door-to-door population census since 1998 last month, working in conjunction with the military, which has deployed 200,000 troops to provide security for the exercise.

At least 119,000 government employees are taking part in the exercise as enumerators.

The lead-up to the census has been marked by political debate on how the results may show changing demographics - potentially redrawing electoral constituencies - across the country.

Television footage from the scene showed a destroyed vehicle and debris scattered on the road, as police formed a security cordon around the site’s perimeter.

Surge in violence

Pakistan has seen a surge in violence in the past two months, starting with a series of attacks that killed more than 130 people in mid-February.

Those attacks were claimed by the Pakistan Taliban and the Islamic State of Iraq and the Levant (ISIL) group.

At least 13 people were killed in Lahore when a suicide bomber targeted police at a protest demonstration on February 13

In response, Pakistan’s military announced it was launching a new operation - dubbed Radd-al-Fasaad, or Elimination of Mischief/Chaos - across the country, to cement the gains made against the Pakistan Taliban during a previous three-year operation launched in 2014.

Additional reporting by Alia Chughtai in Karachi