The attack took place at 12:15 local time in the capital, Islamabad, according to a statement from WFP, which added that a number of injured – some of whom are in a critical condition – are being treated in hospital.

“This is a terrible tragedy for the UN and for the whole humanitarian community in Pakistan,” Mr. Ban said in a statement issued in Geneva, where he is currently on an official visit.

“This is a heinous crime committed against those who have been working tirelessly to assist the poor and the vulnerable on the frontlines of hunger and other human suffering in Pakistan,” he added.

WFP Executive Director Josette Sheeran expressed her deepest condolences to the family, friends and colleagues of the staff members who were killed or injured in the attack.

They have been identified as Botan Ahmed Ali Al-Hayawi of Iraq, and Mohammed Wahab, Abid Rehman, Gulrukh Tahir and Farzana Barkat, all of whom are Pakistani nationals.

“All of the victims were humanitarian heroes working on the frontlines of hunger in a country where WFP food assistance is providing a lifeline to millions. This is a tragedy – not just for WFP – but for the whole humanitarian community and for the hungry,” she stated.

The UN Resident Coordinator in Pakistan, Fikret Akcura, said there is no possible justification for this “shocking” crime against humanitarian workers. “We urge Pakistani authorities to place their full attention on arresting the perpetrators who planned and implemented this horrendous act of terrorism.”

Following today’s attack all UN offices in the country have been temporarily closed.

WFP is providing vital food assistance to as many as 10 million people across Pakistan, including emergency relief to as many as 2 million Pakistani civilians who were displaced by conflict in the Swat Valley region earlier this year.

The agency also supports school meal programmes and targets food assistance at vulnerable groups of people across the country.

News Tracker: past stories on this issue

UN humanitarian chief condemns increasing violence against aid workers