Syrian state media say a rocket slammed into a building in the country's northern city of Aleppo on Friday, causing casualties.
Video broadcast on state television showed large parts of the building collapsed, with medics pulling bodies out of the wreckage. The number of dead and wounded is not immediately known.
State media have blamed the attack on a "terrorist group", a term it frequently uses to describe rebels in the 22-month-old uprising against President Bashar al-Assad. But activists say the government launched a military airstrike in the area.
Syrian security personnel, members of the civil defence and civilians gather at the site where a large blast hit a neighborhood of Aleppo, January 18, 2013.
A Free Syrian Army fighter runs for cover at a suburb of Damascus, January 17, 2013.
Residents stand near buildings damaged by missiles fired by a Syrian Air Force fighter jet in Daraya, January 17, 2013.
A Free Syrian Army fighter holds a rifle in the Ain Tarma neighborhood of Damascus, January 15, 2013.
Syrians gather at the scene of an explosion outside Aleppo University, between the university dormitories and the architecture facility, January 15, 2013.
A street vendor sells cotton candy in Aleppo, January 15, 2013.
A woman walks near a crater caused by missiles fired by a Syrian Air Force fighter jet near Idlib, January 15, 2013.
Buildings in Erbeen, near Damascus, damaged by missiles fired by a Syrian Air Force fighter jet, January 15, 2013.
Internally displaced Syrian children sit on a bench at a school in Aleppo, January 14, 2013.
People gather at a site hit by missiles fired by a Syrian Air Force fighter jet in Azaz, north of Aleppo, January 13, 2013.
A Free Syrian Army fighter aims his weapon in the Saif al-Dawlah neighborhood of Aleppo, Syria, January 13, 2013.
A farmer transports a tree which will be used for heating in the countryside of Idlib January 13, 2013.
A boy, standing next to his father, cries as they wait to receive humanitarian aid in the countryside of Idlib January 13, 2013.
Syria's government restricts foreign media from many parts of the country, making it difficult to confirm details of attacks.
Aleppo, Syria's commercial hub and the country's largest city, has been wracked by violence since rebels launched an assault on the city in July 2012.
Earlier this week, twin blasts at Aleppo University killed 87 people and wounded more than 150. Among the dead are students and refugees who had settled at the campus. Each side has blamed the other for that attack.
The Syrian conflict has killed at least 60,000 people since it began in March 2011.
Some information for this report was provided by AP and Reuters.