Islamabad, Sept 20 : At least 40 people were killed, including foreigners and around 100 injured in the suicide blast Islamabad's Marriott Hotel tonight.
Rescue operation is underway to bring out the people trapped inside the hotel.
Emergency has been declared in the hospitals of Rawalpindi and Islamabad.
According to The News, about 1000 kilograms of explosive material was used in the deadly explosion, sources said.
The powerful explosion caused fire in many parts of the hotel besides damaging the buildings around the hotel.
Ambulances rushed to the scene, where a fire also burned, smoke hovered and the carcasses of vehicles were scattered.
There was no immediate claim of responsibility for the blast, and its exact cause was unclear.
According to sources, several senior officers of Central Intelligence Agency (CIA) who are reported to be currently visiting Islamabad were the target of the blast at the Marriott Hotel.
Well placed sources said that Marriott Hotel is usual hotel choice of the US officials and it seems that militants tipped off that certain high level US intelligence officers were currently staying at the hotel.
But Pakistan, a U.S. ally in the war on terror, has faced a wave of militant violence in recent weeks following army-led offensives against insurgents in its border regions, though Islamabad has avoided most of the bloodshed.