A Palestinian refugee camp in the Syrian capital Damascus has been attacked, reportedly by war planes, activists say.
The number of people killed or injured is unclear, but the Syrian Observatory for Human Rights, a UK-based activist group, reported at least eight deaths.
The al-Yarmouk camp houses Palestinians and also Syrians displaced by fighting.
Opposition activists say those killed had been sheltering in a mosque as fighting raged in the surrounding area.
A video posted online, which cannot be verified, showed several dead bodies apparently sprawled in the street and on the steps of the mosque.
The observatory said the attack on Yarmouk was the sixth on Sunday on districts of southern Damascus where rebels have been battling government forces.
Information from opposition activist groups cannot be independently verified.
Violence has been increasing in and around the capital in recent weeks.
Yarmouk is the largest Palestinian refugee camp in Syria.
There are some 500,000 Palestinians in Syria. Their loyalties are divided between the government and the opposition.
In August, at least 20 people were killed in a shopping area during a mortar attack on the camp.Commander 'killed'
In another development, an Islamist rebel group said it had captured a military installation near the war-torn northern city of Aleppo.
A statement from the Tawheed Brigade said it had "fully liberated" the site and taken "at least 100" prisoners.
It added that the brigade's commander had been killed in the battle.
Unconfirmed reports identified the complex as the Hanano Barracks, north-east of the city. Rebels previously seized the barracks in September but were driven out by government troops a few days later.
The site includes an army base, a recruiting centre and a military school.
If confirmed, the loss of the base would be the latest in a series of setbacks for government forces in and around Aleppo.
Earlier this month, rebel fighters captured another large military base west of the city.
Base 111 at Sheikh Suleiman was said to have been captured by jihadists led by the militant al-Nusra Front.
In November, rebels captured another large base nearby at Atarib.
In Aleppo itself, rebels are believed to be still in control of at least half the city, despite attempts by government forces to dislodge them.
As violence across the country intensified, the UN warned of a dramatic rise in refugees fleeing to neighbouring countries.
Speaking in Amman, the head of the UN refugee agency (UNHCR) Antonio Guterres said the number of refugees in Jordan, Turkey and Lebanon could rise from more than 500,000 at the moment to an estimated 1.1 million by June 2013.
He said the worst case scenario predicted a possible 1.8 million refugees.
"This is a brutal conflict that is having dramatic, tragic humanitarian consequences. Both the Syrian people and those countries need and desire enhanced international solidarity," he said.
Mr Guterres announced the setting up of a joint operation centre between UN agencies and the Jordanian government to better coordinate aid.