Many people are reported killed in an airstrike by Syrian government forces in the north of the country on Wednesday.
The attack is said to have happened in the rebel-held town of Azaz.
Reports quoting a local doctor say 30 were killed, with scores wounded.
Pictures posted by activists onto the internet show scenes of distress and chaos as people try desperately to free those trapped in the debris, and to search for other survivors.
There is damage and debris spread over a wide area. The strike reportedly reduced several houses to rubble.
Azaz, just north of the major urban battleground of Aleppo, is where rebels have been holding 11 Lebanese hostages.
A rebel commander has been quoted as saying that a government fighter jet bombed the building where they were.
Seven hostages were taken out, some seriously injured, he said. Unconfirmed reports say four were killed.