Investigators are sifting through the rubble of Peshawar's luxury Pearl Continental Hotel, after a suicide truck bombing killed at least 11 people, including two UN aid workers.
Some news agencies place the death toll as high as 18, while estimates on the number of injured varies from 59 to 70.
Mian Iftikhar Hussain, the information minister of Northwest Frontier Province, is quoted by the French news agency AFP as saying the massive blast was revenge for the Pakistani government's military operation against Taliban ensconced in the country's northwest.
"The blast is a reaction to the army offensive in Swat and Malakand. The possibility of this type of terrorist attack cannot be ruled out in future," Hussain said.
The Pearl Continental Hotel, popular with foreigners, was housing a number of international aid workers who arrived in the city to assist the tens of thousands of people displaced by fighting between government forces and the Taliban in northwest Pakistan.
Security video footage shows militants riding in a white car shooting their way through a security post at the gate of the hotel. A white flatbed truck, presumably packed with explosives, follows the car and hurtles toward the hotel's main building.
The powerful blast brought down part of the five-story hotel's facade and destroyed dozens of cars. Police reportedly estimated that the bomb contained 500 kilograms of explosives.
"We were offering our prayers when firing started, and everybody began shouting, 'The terrorists are here'," said taxi driver Jameel Shah. "Then all of a sudden there was a loud blast."
Speaking to RFE/RL from Peshawar, regional expert Fazal Rahim Marwat said that the hotel was considered the "safest hotel" in Peshawar. It is surrounded by many important government and military offices and was widely used by aid workers and diplomats.
"The truth is that after the Swat operation, the government here has been doing all it can [to improve security]. It has established check posts and conducts regular searches," Marwat said.
"The truth is that no public place was safer than where the bombing happened yesterday, because the main hotel building was far away from the front gates were visitors were searched. They had sniffer dogs and security cameras and even the V.I.Ps were thoroughly searched," he said.
Marwat suggested that the hotel was targeted because the militants wanted to send a message to Westerners that no place in Peshawar is safe for them.
The Office of the UN High Commissioner for Refugees confirmed that Aleksandar Vorkapic, a Serbian working for the aid agency, was killed. The United Nations reported that Perseveranda So, a UNICEF employee from the Philippines, was also killed.
"This is an attack on the very humanitarian principles to which Persy was dedicated, and it is reprehensible and unacceptable," UNICEF's executive director, Ann Veneman, said in a statement.
UN Secretary-General Ban Ki-moon also condemned the attack.
Top city administrator Sahibzada Anis said that a German woman working for UNICEF, a British man, and a Nigerian man were also among the 70 wounded.
A similar suicide truck bomb targeting the Marriott Hotel in Islamabad in September killed 55 people.