They met and took samples from victims of the attack in the eastern Ghouta region, which reportedly killed hundreds of Syrian civilians, according to a doctor who spoke to Reuters.
Agence France-Presse reported that the inspectors have now left Moadamiya.
UN Secretary-General Ban Ki-moon said the team's vehicle "was attacked by an unknown sniper, but despite such very difficult circumstances, our team returned to Damascus and replaced their car and proceeded to a suburb of Damascus to carry on their investigation," after speaking to his under-secretary who is in Damascus.
"They visited two hospitals, they interviewed witnesses, survivors and doctors, they also collected some samples," Ban said, noting that the UN would "register a strong complaint to the Syrian Government and authorities of opposition forces" so that an attack like that on the UN convoy would not happen again. Earlier, unidentified snipers in Syria shot and disabled a vehicle carrying the UN team on their way to investigate the suspected site.
The UN quickly released a statement, asking that rebels and the forces of President Bashar al-Assad allow investigators to safely enter the area and do their job.
"The first vehicle of the Chemical Weapons Investigation Team was deliberately shot at multiple times by unidentified snipers in the buffer zone area," a spokesman said.
No injuries were reported, but the lead car was damaged, causing investigators to return to a government checkpoint where they obtained a new vehicle and return to the site.
"It has to be stressed again that all sides need to extend their cooperation so that the team can safely carry out their important work," the spokesman added. Syrian state media claimed an unknown source had told them "armed terrorist groups opened fire on members of the UN team" as they were entering the al-Muadamiya area.
The UN inspection team entered Syria on Aug. 18 with the government's approval to visit three sites suspected of being subjected to chemical weapons attacks.
Another incident occurred on Aug. 21, while the UN team was in the country, with doctors and activists claiming an unidentified nerve agent had killed hundreds of innocent civilians. Investigators were then granted access to the site outside Damascus.
The UN team was on its way to the site of the latest alleged attack to collect tissue, soil, blood and urine samples from victims when it came under attack. Even if the team were to reach the area, the United States said evidence from the attack has likely deteriorated or been destroyed by heavy government shelling.
However, experts said evidence of any nerve agent would remain traceable in hair and tissue from victims of the alleged attack.
Assad has repeatedly dismissed the idea that his forces have used chemical weapons, while a senior Obama administration official recently said there was “very little doubt” the regime had used chemical weapons against civilians.
In light of the most recent alleged chemical weapons attack, the Syrian opposition said Monday that the Geneva talks, an effort to engage both sides of the Syrian conflict backed by the United States and Russia, were off the table.
Britain, France, Turkey and Germany have all said they would support some sort of international response to the alleged chemical attacks, even if the UN Security Council remains split along its usual political lines, with Russia — Assad's stalwart ally — attempting to block military intervention.
On Monday, Chancellor Angela Merkel's spokesman Steffen Seibert said Germany would back a military response in Syria if it were somehow proven that Assad's forces had used chemical weapons.
"Germany would be among those who consider consequences to be appropriate," said Foreign Minister Guido Westerwelle in a statement on Monday.
Merkel spoke with France's President Francois Hollande and Britain's Prime Minister David Cameron and said any alleged use of chemical weapons in Syria breaks a taboo and requires an international response.
The United States and its allies believe Syria has stockpiles of sarin and mustard gas, though the regime has never admitted to possessing chemical weapons.
This video, provided by activists, allegedly shows the UN inspectors talking to victims at the site of the attack on Monday: