Fighting is reported to be continuing in the Syrian city of Homs, where activists say at least 50 people were killed by government forces.
Rebel fighters have told the BBC that government tanks and artillery are being positioned around part of the city which is under opposition control.
Early accounts of the casualties talked of as many as 200 deaths, but one of the main activist groups later revised its confirmed toll down to 55.
The Syrian government denies the army shelled the city.
The latest violence comes as Russia and China used their veto to block a UN resolution condemning the Syrian government's crackdown on an uprising which began 11 months ago.
The draft resolution backs an Arab League plan for Syrian President Basher al-Assad to step aside. The other 13 council members voted in favour.
Residents of Homs said the bombardment earlier on Saturday was the most violent episode the city has suffered in months of defiance, the BBC reports.
Field hospitals set up in mosques and other buildings were flooded with wounded and issued appeals for blood donations.
Activists said other medical supplies were also running out and that dozens of seriously injured would die if they didn't receive proper treatment very soon.
But one of the local activist groups, the Local Co-ordination Committees, has substantially reduced initial estimates of the number killed.
It said it had documented just 55 killed in Homs, including outlying areas.
International media outlets are restricted in Syria, making it difficult to verify the claims of either side.
Homs was one of the first cities to join anti-Assad protests, and became one of the focal points of dissent after government forces fired on crowds in April last year. Many army defectors have sought refuge in the city.