People searched for survivors in the rubble in Aleppo
Three missiles have crashed into residential areas of Syria's northern city of Aleppo, killing at least 12 civilians, activists say.
Video footage posted online claims to show the aftermath, with people carrying away the wounded and a wide area reduced to rubble.
Activists say families are buried under the rubble in one neighbourhood.
Meanwhile, opposition politicians say they have agreed to form a government for rebel-held areas.
Umbrella group the Syrian National Coalition, meeting in Cairo, said it would meet again in Istanbul on 2 March to name a prime minister.
The UN estimates that about 70,000 people have died since the uprising against President Bashar al-Assad's regime began in March 2011.'Horrible sight'
The reasons for the latest attack are unclear, and it is also not clear who launched the missiles.
Earlier this week, activists accused the government forces of targeting other areas of Aleppo with Russian-made Scud-type missiles.
Video footage allegedly of the latest incident shows chaotic scenes, but the darkness of the images makes it difficult to identify the type or size of the rockets.
An activist called Baraa al-Youssef told Reuters news agency that 30 homes had been destroyed by one of the rockets.
"Nothing can describe it, it's a horrible sight," he said.
The UK-based Syrian Observatory for Human Rights said 12 bodies had been recovered and more than 50 people had been wounded.Risky proposition
In the early months of the uprising Aleppo, Syria's commercial capital, was largely spared the violence.
But the course of the conflict dramatically shifted in summer 2012, and the northern city become an intense battleground.
Many thousands have fled the violence, and in recent months the rebels and government forces appear to have reached stalemate, neither side being able to gain the upper hand.
Much of Syria is in a similar situation, and even areas controlled by the rebels are subject to intense bombardment from the air.
The political opponents of Mr Assad mostly live in exile.
They have floated the idea of a transitional government ever since their opposition coalition was formed in Qatar last November.
The BBC's Jim Muir in Cairo says it is a risky and complicated proposition, and that is why it is taking so long.
If the transitional government fails to attract sufficient financial and diplomatic support, and if it cannot operate inside rebel-held areas of Syria, the coalition may lose its already shaky credibility, our correpondent adds.
But if the coalition does not try, it risks leaving those areas to slide further into the hands of the radical Islamist factions that are making the running on the ground, he says.