Two powerful blasts in quick succession rocked the Syrian capital at morning rush hour Thursday, killing and wounding dozens of people, state television said, blaming the attacks on "terrorists."
"Two explosions caused by terrorists took place on the freeway in the south of Damascus," the television said, adding that the blasts occurred "as people were heading to work and children to school."
Residents said the explosions rattled windows and sent plumes of smoke billowing into the sky.
Television footage at the site of the blasts, which took place on a freeway in the south of the capital, showed an apocalyptic scene with charred bodies and the carcasses of vehicles with smoke still rising from them.
The report did not give a breakdown on the number of people killed and those wounded, but said most of the casualties were civilians.
An AFP photographer at the site said a number of civilian cars were destroyed and buildings damaged. A crater three metres (10 feet) wide was caused by one of the explosions.
The Syrian Observatory for Human Rights, a Britain-based monitoring group, said the explosions occurred at an intelligence services base in Damascus. It said at least one of the blasts was caused by a car bomb.
Damascus has been the target of a number of bombs in past months as President Bashar al-Assad faces a revolt against his regime which his forces are attempting to crush.
The blasts came a day after a bomb attack on a UN observer convoy in the southern city of Daraa, which injured six Syrian troops escorting the vehicles.
Responding to the Daraa attack, UN leader Ban Ki-moon warned Syria's government and opposition there is only a "brief window" to avoid civil war and indicated the future of the ceasefire monitoring mission was in doubt.
Highlighting an "alarming upsurge" of roadside bombs, alongside government attacks, Ban said both sides "must realise that we have a brief window to stop the violence, a brief opportunity to create an opening for political engagement between the government and those seeking change."
The Observatory says that almost 12,000 people, mostly civilians, have been killed in Syria since the revolt, inspired by Arab Spring uprisings, broke out in March last year.
About 800 of them have died since a UN-backed truce was supposed to have taken effect on April 12.
Damascus was hit by two blasts on May 6, with three soldiers wounded in one of the attacks. Television footage showed a mangled car destroyed by one of the explosions.
A deadly suicide bombing at Zein al-Abidin mosque in the capital's central Midan district on April 27 killed 11 people and wounded dozens, according to state media.
An Islamist group calling itself Al-Nusra Front had earlier claimed responsibility for a deadly suicide bombing on April 20 near the Syrian city of Hama that targeted a restaurant used by the security forces.
The Syrian authorities regularly blame the blasts on "terrorist groups" they say are behind the violence that has swept the country for the past 14 months.
The opposition accuses regime forces of being behind the bombings in an attempt to discredit protesters demanding the ouster of Assad.