The fact that most of those dead are from the Syrian security forces means that one of the terrorist groups fighting the Assad regime - including Al-Qaeda in Iraq - was probably responsible for the blasts.
The near-simultaneous explosions hit the al-Qazaz district just before 8 a.m. (0500 GMT), residents said. One punched a crater three meters (10 feet) deep in the city's southern ring road. Bloodied corpses and body parts could be seen on the road.
State television also showed at least one overturned lorry. Walls of buildings on each side of the avenue had collapsed.
One resident reported limited damage to the facade of the nearby Palestine Branch Military Intelligence centre, one of the most feared of more than 20 Syrian secret police agencies.
The huge walled complex was the target of a 2008 bombing which killed 17 people and which authorities blamed on Islamist militants. Some residents said access to the section of ring road near the Palestine Branch was later restricted.
The opposition Syrian Observatory for Human Rights put the death toll from the bombings at 59 and said most of them worked for the security forces. No group has claimed responsibility.
Rami Abdulrahman, head of the British-based Observatory, said 849 people - 628 civilians and 221 soldiers, of whom 31 were defectors - had been killed since the April 12 truce. The toll did not include Thursday's deaths.
The attacks occurred a day after a bomb blew up near U.N. observers monitoring the ceasefire, which state forces and rebels have both violated, and two weeks after authorities said a suicide bomber killed at least nine people in Damascus.
"This is yet another example of the suffering brought upon the people of Syria from acts of violence," said Major-General Robert Mood, leader of the U.N. monitors, who visited the scene.
Maj.Gen. Mood, a Norwegian, is slowly gathering his force of 300 monitors to patrol Syrian cities and towns where Assad's military is facing off with the protestors. But it will be several more weeks before he gets his full complement of monitors, and by that time, the cease fire is likely to be a dead letter.