ISLAMABAD, PAKISTAN - A bomb exploded on Monday at an office of the U.N. World Food Programme (WFP) in the Pakistani capital, Islamabad, killing two people and wounding four, police said.

"We moved six wounded people to hospital and two of them are dead," senior city police official Bin Yameen told reporters.

One of the dead was a foreigner, while the other was a Pakistani woman, said Waseem Khawaja, a doctor and spokesman at the Pakistan Institute of Medical Sciences, the main government hospital in Islamabad.

The bomb was planted in the WFP office, a U.N. official said.

Pakistan is battling Islamist militants in its northwest who have set off numerous bombs in towns and cities aimed at the security forces as well as government and foreign targets.