The attack outside the five-star Marriott Hotel — not far from key government buildings such as the parliament house, the presidency, the prime minister’s house and Pakistan Television headquarters — happened early in the evening shortly after Iftar and hours after President Asif Ali Zardari addressed a joint session of the two houses of parliament where he said Pakistan would not allow the use of its territory for terrorist activities.

In an address to the nation after Saturday midnight, President Asif Ali Zardari vowed to “continue to fight terrorism and extremism”.

“The government will continue to fight terrorism and extremism in all its forms and manifestations and such dastardly acts cannot dent the government’s commitment to fight this menace,” Mr Zardari said.

Prime Minister Yousuf Raza Gilani joined the president in condemning the massive attack.

The president and the prime minister have ordered authorities to conduct an inquiry into the blast and to submit a report within 12 hours.

Information Minister Sherry Rehman told reporters that “such cowardly acts cannot deter the government’s commitment to fight terrorism and extremism”.

There was no immediate report of any foreigner killed in the blast that set off fires, apparently due to gas leakages, in most of the five-floor hotel in Islamabad’s F-5 sector. But police and doctors said some foreigners were among the wounded taken to hospitals.

An Iftar dinner, also attended by President Zardari, was being held at the prime minister’s house at the time of the blast, which shook the whole of Islamabad, causing panic in markets and residential districts.

Places as far away as 30kms from the hotel reverberated with the thunder of the explosion. Almost all the 290 rooms of the hotel, which was occupied by both local and foreign guests, were gutted.

Four foreigners — one American, two Saudis and one Filipino — were killed and seven — two Saudis, three Germans and two British nationals — were wounded.

According to earlier unofficial reports, over 40 people were killed mostly from those attending an Iftar party at the hotel’s Marquee Hall located on front side of the building.

The blast caused a huge crater, 20 feet deep and 40 feet wide, at the main entrance of the hotel where, according to some witnesses, a white mini-truck rammed into the steel barrier at 8.05pm.

Interior Secretary Syed Kamal Shah told reporters outside the hotel that it was a “unique blast”.

Rehman Malik, the adviser to the prime minister on interior, said preliminary investigations revealed that some 1000kgs of explosive material had been used in the blast. He put the death toll at 28 and the number of the injured at 50.

Mr Malik revealed the interior ministry had received intelligence that terrorists could strike the Parliament Building on the occasion of presidential address to the joint session of parliament.

“As a result of the report, security was already tightened in the federal capital and additional police and rangers were called into the city to foil designs of the terrorists.”

Outside the hotel, the blast destroyed over 150 cars parked within a radius of 500 feet, uprooted a number of trees and electricity poles, and damaged nearby buildings, including the Frontier House, the Evacuee Trust Building, and those housing the Federal Public Service Commission, Pakistan Television, and government residential buildings.

The timing of the blast was significant as it coincided with an Iftar dinner at the Prime Minister’s House only half a kilometre away.

Some witnesses said the driver of the mini-truck first fired three shots at security guards manning the checkpost of the hotel and then hit the steel barrier. The truck soon turned into a heap of twisted metal, splinters flying in all directions and landing at a good distance from the scene.

A mangled door was found deep inside the crater.

The authorities concerned have been ordered to conduct an inquiry into the bombing and submit a report within 12 hours.

A team comprising police and intelligence officials has been set up to carry out the inquiry.

Sadruddin Hashwani, the owner of the Marriott, told reporters outside the burning building that some 300 people were in the Marquee Hall attending an Iftar function, and about 1,000 guests were staying at the hotel.

Six hundred members of the staff were present in the building when tragedy struck.

Mr Hashwani said almost all the guests had been evacuated. But the Marquee Hall bore the brunt of the strike

Saudi Ambassador Alfawad Al Aseeri rushed to the scene after hearing reports that five employees of the Saudi Arabian Airlines were missing.

Four other employees were admitted to hospital after receiving injuries.

“I hope that the missing crew members are safe or they would have been shifted to some private hospitals for treatment,” he said.

According to some sources, a number of US marines who had put up at the Marriott sustained injuries. They were due to leave for Kabul on Sunday.

A law enforcement official said in all likelihood “personnel of a US security agency” were the attackers’ target.

Some police sources said two explosive-laden vehicles were used in the attack.

They said at first the attackers, riding in a car, opened fire on the security staff at the hotel gate to clear the way and later they blew up their vehicle. Seconds later, the explosive-laden truck hit the security cordon.

A senior police official said 1000kgs of explosive material had been used by the terrorists.

He said the two vehicles carrying explosive travelled through Khyaban-i-Margalla road and then hit the Marriot Hotel avoiding a red zone.

Well-equipped security officers from the US embassy were seen on the spot soon after the explosions. However, they left the scene shortly afterwards.

Those killed included two Frontier Constabulary (FC) officials, six private security guards standing at the hotel gate and a passer-by civilian woman. The injured included two British nationals, three Germans and two Saudis.

A Pims hospital spokesman said 25 dead bodies including two of the FC personnel, six security guards, and two other persons were brought in the hospital. Seven dead bodies were shifted to the Poly Clinic Hospital, two to the CDA hospital.

The hotel building was engulfed in flames, leaving its rooms, café and restaurant in ruined, while several people remained trapped inside their room for several hours due to fire that blocked the emergency exits.

Police said the blast occurred when a vehicle — believed to be a dumper approached the hotel gate and the suicide bomber exploded it when was stopped by the security personnel.

The blast left a 20feet deep and 35 feet in radius crater and destroyed the entire front of the hotel and also shattered down the window pans of nearby buildings. Street light poles and trees were uprooted and dozens of vehicles parked outside the hotel were damaged.The sound of the blast that was heard miles away sent a wave of panic and fear among the resident of the federal capital territory and Rawalpindi. More than 1500 guests, including foreigners were dining in the hotel when the terrorist attack occurred.Ambulances, fire engines and rescue teams rushed to the scene of the blast. The entire area was cordoned off by the security personnel. Later, the troops were called to help the local administration in pulling out the people trapped inside the hotels that was engulfed.

The Marriot Hotel has been popular among the foreigners visiting Islamabad and had been previously targeted by terrorists.

The attack came a few hours after the newly elected president Asif Ali Zardari made his first address to the joint session of the parliaments amid tight security.

The president said in his address that he would not allow Pakistan’s territory to use for terrorist activities.

The Marriot Hotel is located near government buildings, including President House, Parliament building, Prime Minister House, and right opposite to the Sindh House and judicial colony.

Strict security checks are carried out at the hotel gate. The scene of the blast was closed to the security check point.

Abdul Hameed, a police constable who was on duty close to the hotel had recorded his last few worded wireless massage saying as: “I tried to stop a dumper but it exploded at the gate.”

Some women and children staying in the 290 room-hotel went on rooftop of the hotel as the fire erupted. They were shouting for help.

Ikhlaq Ahmed, one of the hotel employees said he was in side the hotel when a small blast occurred, seconds later another explosive laden dumper appeared at the gate and exploded.

No militant group has claimed responsibility of the today’s terrorist attack on the hotel so far.

At least seven of the injured victims, including a female were shifted to Benazir Bhutto hospital Rawalpindi. Shortly after the explosion, emergency was declared in all the government run hospitals in Rawalpindi.

A red-alert was declared in Rawalpindi and night police patrol was also started.