Bombs have exploded at three international hotels in the Jordanian capital,Amman. At least 57 people are known to be dead and hundreds have been injured. Its feared the death toll could rise as many of those injured are in a serious condition.Jordan has closed its borders indefinitely. The country’s airports are still open but strict security measures have been put in place. Suicide bombers are being blamed for at least two of the attacks. The explosions happened at the Radisson Hotel, the Hyatt and the Days Inn. All the hotels are in the centre of Amman, an area popular with tourists and business people. The casualties may include a number of foreigners. The majority of those injured were guests at a wedding reception at the Radisson Hotel. It is thought one of the suicide bombers detonated explosives strapped around his waist once inside the room. Jordan is a key ally of the United States, with strong links to Israel. As such, it has been seen as a likely target for terrorist attacks.Last August a series of rockets were launched at american buildings in the Jordanian port of Aqaba.