As world leaders deadlock over what to do about Syria at the United Nations summit in New York, the war-torn country has experienced one of the bloodiest days of its 18-month civil war. The opposition group Local Coordination Committees of Syria claims 343 deaths in a single day on Wednesday, the highest death toll since fighting began in March 2011, CNN reports. Meanwhile, the British-based Syrian Observatory for Human Rights released a report Thursday claiming more than 300 deaths Wednesday for a total of 30,000 deaths since March 2011, Reuters reports.

The reports attributed at least 40 deaths to a massacre by Syrian troops in al-Dhiyabia, a town south of Damascus, where victims of the alleged attack were shown in a YouTube video revealing corpses of men from the age of 60 to their teens. The 343 reported deaths would place Wednesday ahead of August 25, 2012, when 330 people were reportedly killed. While figures of the two reports could not be independently verified given restrictions on journalists working in the country, other reports from yesterday and this morning have chronicled a brutal uptick in violence in the country against both opposition forces and Syrian troops loyal to President Bashar al-Assad.

For instance, the Lebanese TV station Al Manar is broadcasting footage of Syrian forces pushing back rebels from a military building in Damascus following a car bomb attack, reports the Associated Press. "The footage showed the bodies of three rebels inside the building after government troops took control. The bomb attacks highlighted the regime's growing vulnerability as rebels fighting to oust President Bashar Assad grow bolder." The footage appears below:

Yesterday, Reuters reported on attacks in the Dhiyabia area, where footage showed men who "appeared to have been shot in the forehead, face or neck." Meanwhile, the United Nations reports that there are now 294,000 Syrians either registered as refugees or waiting to register. "It confirmed that it expects the number to increase to 700,000 by the end of the year," reports The Guardian. "The number of people crossing the border into neighbouring countries has reached up to 3,000 people every day."

All of this, of course, happening in the backdrop of fiery UN speeches denouncing the violence to little effect. On Wednesday, British Prime Minister David Cameron gave his strongest attack yet on UN inaction, saying the killing of children has created a "terrible stain" on the UN. "And in particular, a stain on those who have failed to stand up to these atrocities and in some cases aided and abetted Assad's reign of terror," he said. Meanwhile, Egyptian President Mohammed Morsi urged an end to the civil war, calling it the "tragedy of the age."