iStock/Thinkstock(NEW YORK) — A United Nations security team came under fire on Tuesday during a visit to the site of a suspected chemical attack in the Syrian town of Douma, the head of the Organization for the Prohibition of Chemical Weapons said on Wednesday.

The team was in Douma to survey conditions before chemical weapons experts were to inspect the site. Gunshots were fired at the U.N. security team and an explosive was detonated before the team returned to Damascus, OPCW Director-General Ahmet Uzumcu said. International chemical weapons inspectors were expected to visit the site on Wednesday, but the visit has now been postponed and it is unknown when it will take place.

“At present, we do not know when the [Fact-Finding Mission] team can be deployed to Douma,” Uzumcu told the OPCW’s Executive Council, adding that he will only consider deploying the inspectors once the U.N. security team determines that it is safe and only if the inspectors get unhindered access to the site.

The OPCW inspectors are in Syria to investigate a suspected gas attack, which took place on April 7 in Douma. The alleged attack killed scores of civilians, according to activists, rescue workers and Western countries.

In response, the United States, the U.K. and France fired missiles at three Syrian targets on Saturday. The targets included a scientific research center in the greater Damascus area described by U.S. officials as a center for research, development, production and testing of chemical weapons.

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