The Syrian authorities say at least 27 people have been killed and 97 wounded in two explosions in the capital, Damascus.
Describing the blasts as terrorist attacks, state television says preliminary reports suggest that vehicles packed with explosives were detonated. It says intelligence and police buildings were hit.
Pictures were shown of charred bodies, burnt-out vehicles and bloodstains on the streets, as well as injured people being treated in hospital.
"All our windows and doors are blown out," a local resident, Majed Seibiyah, told the Associated Press news agency.
"I was sleeping when I heard a sound like an earthquake. I didn't grasp what was happening until I heard screaming in the street."
Details of the reports cannot be independently verified; foreign journalists have very restricted access to Syria.
Annan about to send team to Damascus
Dozens of people have been killed in bomb attacks in Damascus and Syria's second city, Aleppo, in recent months - attacks that the government has also blamed on terrorists.
The rebel opposition has accused the authorities of staging some of those incidents.
The BBC reports the timing of the latest bomb blasts will raise eyebrows: they occurred a day before United Nations/Arab League envoy Kofi Annan sends a technical team to Damascus.
Similar explosions took place in the capital just as an Arab League mission arrived in the country.
Mr Annan wants to find a political solution to the Syrian crisis but President Bashar al-Assad has said that will not succeed while "terrorist groups" are operating in the country.
Fresh anti-government protests were held on Friday in cities across Syria.