(CNN) -- A series of deadly explosions rocked parts of Damascus Saturday with some of the targets being Syrian government facilities, witnesses and state television reported.
At least 27 people were killed and 97 others were wounded in two blasts, state TV reported, quoting Syrian Health Minister Wael Halki.
The state-run Syrian Arab News Agency (SANA) said early indications were that two booby-trapped cars exploded in crowded areas. It put the death toll at 24, with 140 people injured and serious damage caused to surrounding buildings.
One explosion occurred near the customs criminal investigations department, witnesses said. Another struck near the Air Force intelligence headquarters in Tahrir Square in a different area of the city.
State TV reports blamed the explosions on "terrorists."
Kofi Annan advises caution on Syria
The explosion by the customs criminal investigations department was only a short distance from Umayyad Square, where state media reported Friday that huge numbers turned out to demonstrate in support of the regime of President Bashar al-Assad.
The blast near the Air Force intelligence headquarters was close to where twin bombings struck the offices of two security branches in Damascus in December. The government blamed terrorists inside and outside of Syria, but the opposition called the attacks the work of the regime. The capital was hit by another blast in January.
The Local Coordination Committees (LCC) of Syria, an opposition activist network, reported seeing a large white cloud of smoke hanging above Damascus Friday.
Sixteen people were killed elsewhere in Syria Saturday, the LCC said, including a child, two military defectors, and two people under torture. The child, 11, died in the city of Raqqa when security forces fired on a funeral procession, the LCC said.
Six other deaths occurred in Raqqa and four in Homs, the LCC said, with the others reported in Jabal al-Zawiyah, the town of Tremseh, in Hama province, and Inkhel, in Daraa province.
The Syrian Observatory for Human Rights, a London-based opposition group, said two policemen were killed and three more injured after an attack by unidentified gunmen early Saturday at a police station in the town of Haritan, in the Aleppo region.
The latest violence comes a day after Kofi Annan, special joint U.N-Arab League envoy, briefed the U.N. Security Council Friday on the Syrian crisis via a private teleconference.
Speaking to reporters afterward from Geneva, Annan said he was working hard to stop the yearlong violence in Syria and "get unimpeded access" for humanitarian relief.
"I'm doing my best with the support of everyone to try to find a peaceful solution," Annan said. "The Syrian people want to get on with their lives. They are tired and they suffered a lot."
He said U.N. humanitarian agencies are to arrive in Syria this weekend "if they are not there already, to start their mission with the Syrian government."
The former U.N. secretary-general said the situation in Syria is "much more complex" than that in Libya or other nations. "It's a conflict in a region of the world that has seen many, many traumatic events. I think we need to handle the situation in Syria very, very carefully," he said. "Any miscalculation that leads to major escalation will have impact in the region."
Asked about the prospects of a coalition government, Annan said such a development would have to emerge from talks among Syrians.
U.N. Security Council members are backing Annan's efforts, said Mark Lyall Grant, the British ambassador to the United Nations and the current council president.
Grant didn't disclose details about the meeting but told reporters the session was "comprehensive."
Bashar Jaafari, the Syrian ambassador to the United Nations, also told reporters that "Syria is committed to making Mr. Annan's mission successful."
Annan met last weekend with the Syrian president in Damascus and the Syrian opposition in Turkey in an effort to end the violence that has swept the nation since Syrian security forces cracked down on protesters a year ago. He described the atmosphere in the talks as "welcoming and correct."
Annan's efforts came as shelling and arrests in the country intensified. Peaceful marchers took to the streets Friday in nationwide protests calling for "immediate military intervention," the theme of the day's demonstrations and a reference to opposition calls for outside military intervention.
Most reports from inside the country indicate the regime is slaughtering civilians to wipe out dissidents seeking al-Assad's ouster. The al-Assad family has ruled Syria for more than four decades.
But al-Assad's regime has said "armed terrorist groups" are behind the bloodshed in Syria and says it has popular support for its actions.
The Syrian government Friday underscored its position on terror in letters to top U.N. officials, including U.N. Secretary-General Ban Ki-moon. It said it was protecting its citizens from "terrorists" who are slaughtering and murdering "innocent citizens."
The government said Syria is working to find a political solution to the crisis and wants to cooperate with Annan.
More than 8,000 people have died in the conflict, according to the United Nations, but opposition activists say the overall toll is more than 9,000, most of them civilians.