Two suicide car bombs ripped through the Syrian capital on Thursday, killing 55 people and shaving the facade off a military intelligence building in the deadliest explosions since the country’s uprising began 14 months ago, the Interior Ministry said.

Residents told an Associated Press reporter that the blasts happened in quick succession during morning rush hour, with an initial small explosion followed by a larger bomb that appeared aimed at onlookers and rescue crews arriving at the scene. Paramedics wearing rubber gloves collected human remains from the pavement as heavily damaged cars and pickup trucks smoldered.

There was no claim of responsibility for Thursday’s blasts. But an al-Qaeda-inspired group has claimed responsibility for several past explosions, raising fears that terrorist groups are entering the fray and exploiting the chaos.

In addition to the 55 dead, the Ministry also said there were 15 bags of human remains, meaning the death toll was likely to rise.

More than 370 people also were wounded in the attack, according to the Ministry, which is in charge of the country’s internal security. It said the explosives weighed more than 1,000 kg.

Central Damascus is under the tight control of forces loyal to President Bashar Assad but has been struck by several bomb attacks, often targeting security installations or convoys, since the revolt against him began in March 2011.

But the previous attacks happened on a weekend when many people stay home from work, making it less likely for civilians to be killed. Thursday’s blast was similar to attacks waged by al-Qaeda in Iraq, which would bolster past allegations by top U.S. intelligence officials that the terror network from the neighboring country was the likely culprit behind previous bombings in Syria. That raises the possibility that its fighters are infiltrating across the border to take advantage of the political turmoil.

A shadowy group called the Al-Nusra Front has claimed responsibility for some of the attacks in statements posted on militant websites. Little is known about the group, though Western intelligence officials say it could be a front for al-Qaeda’s Iraq branch.

Al-Qaida leader Ayman al-Zawahri called for Mr. Assad’s ouster in February.

“We strongly condemn the twin bomb attacks this morning in Damascus, which seem to have targeted the maximum amount of casualties and damage and which we see as an act of pure terrorism, from what we see initially,” said Michael Mann, spokesman for E.U. foreign policy chief Catherine Ashton.

The Syrian government blames the bombings on the terrorists it says are behind the uprising, which has been the most potent challenge to the Assad family dynasty in Syria in four decades. But opposition leaders and activists routinely blame the regime for orchestrating the attacks, saying they help it demonize the opposition and maintain support among those who fear greater instability.

Syria’s state-run news agency, SANA, posted gruesome pictures of the mangled, charred and bloody corpses and human remains something that it has done after previous bombings, as well. The decision to show such graphic images could be seen as a tactic by the regime to shock Syrians into abandoning any support for the opposition, which it blames for the country’s chaos.

Maj. Gen. Robert Mood, the Norwegian head of the U.N.’s ceasefire monitors in the country, toured the site on Thursday and said the Syrian people do not deserve this “terrible violence.”

“It is not going to solve any problems,” he said, when asked what his message was to those who are carrying out such attacks. “It is only going to create more suffering for women and children.”

The attack occurred a day after a roadside bomb hit a Syrian military truck shortly after Mood rode by in a convoy traveling to the southern city of Daraa, the birthplace of the uprising.

The relentless violence in the country has brought a ceasefire plan brokered by special envoy Kofi Annan to the brink of collapse. The U.N said weeks ago that more than 9,000 people had been killed. Hundreds more have died since as the conflict has become increasingly militarized, with protesters taking up arms or joining forces with army defectors to fight a brutal crackdown by regime forces.

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