Marriott's chairman has spoken of his sadness after the bombing of the group's luxury hotel in Islamabad Pakistan, where at least 50 people are said to have been killed.
Bill Marriott said: "This senseless tragedy and the profound loss of life has left me greatly saddened. My heart goes out to those who've been injured and the families of the victims.
"We put a very high premium on security at Marriott. In this case, I salute the bravery of the security personnel who were right there when the suicide bomber struck. They had stopped the truck just outside the fortified gate. They were examining it when the bomb detonated. Sadly each member of the team was killed.
"These guys were defending the lives of hotel guests and their fellow co-workers. They were killed in the line of their duty."
The chairman, writing on his blog, added that the exact number of dead and injured was not yet known as the situation was "still unfolding".
The blast took place at approximately 7pm local time on Saturday after a large truck pulled up to the security checkpoint of the heavily guarded hotel and exploded. The huge blast engulfed the front of the hotel and ruptured a gas line, which caused a large fire to break out.
Rescue teams are searching the blackened hotel but temperatures remained high and fires were still being put out in some parts. Officials said the main building could still collapse.
The Marriott is in the centre of the city, close to the National Assembly, the main commercial thoroughfare and the national television headquarters. Security has been high at the hotel since a previous attempted suicide bombing in 2007, foiled by a security guard.
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By Gemma Sharkey