Wounded Syrians seek treatment at a hospital just north of the Turkish border.

Many of them children -- they fled to Turkey for aid after President Bashar al-Assad's air force launched a strike on the rebel-held town of Azaz.

This man, a resident of Azaz, said many more in the city are trapped under debris.

One activist in the town said at least 30 bodies had been found after the attack, and rescuers were searching for more.

Assad's forces have increasingly used helicopter gunships and warplanes against the lightly-armed insurgents -- elements in fresh accusations of war crimes levelled by United Nations human rights investigators on Wednesday.

Opposition sources say at least 18,000 people have been killed since the revolt against Assad began in March 2011.