A suicide car bomber killed at least two people and wounded 19 others in an attack on a U.S. consulate vehicle in northwestern Pakistan.

The bombing occurred as the vehicle travelled Monday through an area housing various international organizations, including the United Nations, in the northwestern city of Peshawar.

The U.S. embassy in Islamabad says two Americans and two Pakistani working at the consulate were among the 19 wounded in what it described as “an apparent terrorist attack.”

Earlier, Pakistani officials said the blast killed two Americans, but the consulate said they only received non life-threatening wounds.

Police say the bomber's vehicle was loaded with 110 kilograms of explosives.

No one has claimed responsibility for the attack.

Peshawar is located on the border Pakistan's semi-autonomous tribal region.

The Pakistani Taliban, the Afghan Taliban, al-Qaida and affiliated militant groups are entrenched in the tribal regions and take advantage of the porous border to launch attacks against NATO and Afghan forces in Afghanistan.