TARTUS, Syria -- In a setback for a United Nations-brokered aid effort, a convoy carrying humanitarian assistance to civilians trapped in the center of the Syrian city of Homs on Saturday was met with gunfire and shelling, breaking a cease-fire.
The Syrian Arab Red Crescent said on its Facebook page that one volunteer was injured, without releasing further details. But the group said that aid had been delivered to the besieged Old City.
The Syrian state news agency reported that four Red Crescent staffers were hurt in the attack.
The aid convoy came under attack from both rifle fire and mortars from "armed terrorist groups," the official media reported, using the government's standard label for rebels.
Various antigovernment activists blamed the attack on the Syrian military in comments to news agencies and on the Internet.
The Red Crescent said two truckloads of food and other aid were delivered to the Old City. A photo released by the group on its Twitter account showed a pair of trucks being unloaded amid the rubble. The group said it was able to deliver 250 food parcels and 190 parcels containing detergents and medicines, the Associated Press reported.
The Old City of Homs remains in the hands of various factions of antigovernment rebels, though the area is surrounded by the Syrian military. About 2,500 civilians are believed to be living in the ancient quarter, lacking sufficient food and other staples.
The plight of civilians trapped in Old Homs has received global attention and was a high-profile issue during Syrian peace talks in Geneva last month. The Syrian government and United Nations officials have pledged to do what they can to aid the residents.
The current aid effort involves a daily cease-fire to allow deliveries of supplies into the Old City and the evacuation of civilians who want to leave. U.N. officials said the rebels and the government had agreed to a daily cessation of hostilities for humanitarian reasons.
But the cease-fire has now been broken on both days of the aid operation, which began Friday with the evacuation of 83 civilians.
On both days, Syrian military forces and police accompanied aid vehicles to a point close to the entrance to the Old City, heavily damaged in more than two years of fighting.
On Saturday, the official media said, one aid vehicle turned back because it had been shot five times by a sniper, while another returned when an "explosive device" detonated on the road, impeding its progress.
Still, reports indicated that two trucks carrying food and other humanitarian aid were able to enter the Old City.
The previous successful aid delivery to the Old City had taken place in May 2012, officials said.
The governor of Homs province, Talal Barazi, accused various rebel factions operating in the Old City of trying to seize the aid and diverting its entry to areas under their control.
Humanitarian groups called on both sides to respect the neutrality of the aid operation and to refrain from firing on the convoys. Officials vowed the aid operation would continue despite the violations of the cease-fire.