UN chemical weapons inspectors began their investigation of an alleged poison gas attack in Syria after their convoy came under fire from unidentified snipers.
The convoy of six vehicles was shot at on Monday in the buffer zone between rebel and government areas near Damascus as it travelled to Moadamiya and Ghouta, the sites of the suspected attack last Wednesday.
"The first vehicle of the investigation team was deliberately shot at multiple times by unidentified snipers," UN spokesman Martin Nesirky said. No one was injured and a replacement vehicle was obtained, he added.
He later told Al Jazeera that the convoy had managed to reach Moadamiya, and had visited two field hospitals to take samples and interview victims.
"They are technical and medical specialists. Their aim is to collect blood and soil samples. They can also collect witness testimony. They will then analyse the samples, along with evidence, to determine what happened."
However, he said that the inspectors' mandate was only to determine whether chemical agents were used - not who used them.
The inspectors later returned to their base in Damascus.
The alleged chemical weapons attack on Wednesday killed 355 people and injured thousands, according to the aid group Medecins Sans Frontieres.
Western powers blame the Syrian regime, and say that potential evidence in the area has probably been destroyed by heavy government shelling over the past five days.
On the diplomatic front, Francois Hollande, the French president, told his US counterpart Barack Obama on Sunday that he concluded that the Syrian regime was behind the attack.
"The two presidents agreed to stay in close contact to arrive at a joint response to this unprecedented aggression," Hollande's office said.
William Hague, the UK foreign secretary, also said that evidence of a chemical attack may have been destroyed.
"The fact is that much of the evidence could have been destroyed by that artillery bombardment," he said on Sunday.
The government of Bashar al-Assad has denied responsibility for Wednesday's attack and blamed the rebels fighting Assad's forces of the same.
The rebels have held the regime forces responsible for the attack.
On Monday, the Russian foreign minister Sergei Lavrov said that the West had no proof to back claims that the Syria regime used chemical weapons.
He warned: "Using force without the approval of the UN Security Council is a very grave violation of international law."
The US government has been under mounting pressure to act, with Obama having defined the use chemical weapons as a "red line' for Syria.