This photo released by the Syrian official news agency SANA, shows smoke rising from burned cars after a huge explosion shook the Sabaa Bahrat Square, one of the capital's biggest roundabouts, in Damascus, Syria, Monday, April. 8, 2013. A car bomb rocked a busy residential and commercial district in central Damascus on Monday, killing more than a dozen with many more injured and sending a huge cloud of black smoke billowing over the capital’s skyline, Syrian state-run media said. (AP Photo/SANA)

Associated Press
This photo released by the Syrian official news agency SANA, shows smoke rising from burned cars after a huge explosion shook the Sabaa Bahrat Square, one of the capital's biggest roundabouts, in Damascus, Syria, Monday, April. 8, 2013. A car bomb rocked a busy residential and commercial district in central Damascus on Monday, killing more than a dozen with many more injured and sending a huge cloud of black smoke billowing over the capital’s skyline, Syrian state-run media said. (AP Photo/SANA)
This photo released by the Syrian official news agency SANA, shows smoke rising from burned cars after a huge explosion shook the Sabaa Bahrat Square, one of the capital's biggest roundabouts, in Damascus, Syria, Monday, April. 8, 2013. A car bomb rocked a busy residential and commercial district in central Damascus on Monday, killing more than a dozen with many more injured and sending a huge cloud of black smoke billowing over the capital’s skyline, Syrian state-run media said. (AP Photo/SANA)