Forty-two people, mostly civilians, have died in an air strike on a mosque in a rebel-held village in northern Syria, a monitoring group says.
The Syrian Observatory for Human Rights said the raid by unidentified planes was in al-Jineh, Aleppo province.
Russian and Syrian aircraft operate there and US warplanes also target jihadist rebels in the region.
The US said it had carried out an air strike, killing several al-Qaeda militants, but had not hit a mosque.
US Central Command originally said the strike took place in neighbouring Idlib province but later clarified that the precise location was unclear.
“We did not target a mosque, but the building that we did target – which was where the meeting [of militants] took place – is about 50ft (15m) from a mosque that is still standing,” spokesman Col John J Thomas said.
The UK-based observatory, which relays information from sources on the ground, said the al-Jineh mosque had been packed with worshippers for evening prayers.
The village lies in one of the main rebel-held regions of Syria.
The attack on Thursday came only a day after at least 31 people were killed in a suicide bombing at the main court complex in the capital, Damascus.
The Damascus bombing was on the sixth anniversary of the start of the uprising against President Bashar al-Assad.
Since then, more than 320,000 people have been killed and 11 million displaced in the conflict, according to activists.