March 17, 2012 -- Updated 0803 GMT (1603 HKT) NEW: One of the buildings targeted was the Air Force intelligence headquarters NEW: Another blast was near where state TV reported a mass pro-Assad rally was held Friday Syrian state TV blames "terrorists" for the blasts, says military personnel and civilians died Twin bombings previously tore through Damascus in December Another struck near the Air Force intelligence headquarters in Tahrir Square in a different area of the city. Syrian state TV did not confirm that that blast occurred. The explosion by the customs criminal investigations department building was only a short distance from Umayyad Square, where state media reported Friday that millions of people 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 latest explosions come 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." Annan met last weekend with Syrian President Bashar al-Assad 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." Most reports from inside the country indicate the regime is slaughtering civilians to wipe out dissidents seeking al-Assad's ouster. 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.