PESHAWAR, Pakistan  Militants opened fire on security guards and rushed a small truck packed with explosives through the gates of a five-star hotel in this northwestern city on Tuesday, detonating the payload in the parking lot and killing at least 11 people and wounding 55, Pakistani officials said.

The blast, powerful enough to leave a crater 6 feet deep and 15 feet wide, collapsed the western wing of the hotel, the Pearl Continental, one of the few in the city that cater to Western visitors. Pakistani television broadcast images of wounded people, panicked and dazed with blood-soaked clothes, being helped out of the smoke-filled lobby. The hotel’s registry was swollen at the time of the attack, which occurred about 10 p.m. local time, with officials working for United Nations agencies and other aid groups tending to the large refugee population that has been displaced by the recent fighting in Pakistan between the Pakistani Army and Taliban insurgents.

One of the dead was a Russian employee of an international aid organization according to a police official at the scene.