The attack in the northern town of Khan Sheikhoun is at least the second time that U.N. observers have been caught up in Syria's violence. Last week, a roadside bomb struck a Syrian military truck in the south of the country just seconds after the head of the U.N. observers team drove by in a convoy.
A video of the bomb attack was posted by activists online. "The front of a U.N. car took a direct hit," activist Fadi al-Yassin, who witnessed the incident, told the Associated Press. "Everyone ran in panic, but the observers stayed in the car. People tried to talk to them, but they wouldn't even open their windows."
Just minutes earlier, Syrian forces fired on a funeral procession, activists said. Yassin and the Britain-based Syrian Observatory for Human Rights said that as many as 20 people may have been killed and said many others were wounded, with some of them in serious condition. It was impossible to independently confirm the toll.
"This is a real massacre, and it took place in the presence of U.N. observers," Rami Abdul-Rahman, head of the Observatory, said of the attack on the funeral. He called for an international investigation and for the monitors to state publicly what they saw.
A video posted by activists online appeared to show the exact moment the U.N. vehicle was struck. The video shows two white vehicles clearly marked "U.N" with people milling around, and two others parked a few yards behind.
The blast blew off the front of the first vehicle and sent up a plume of smoke as people screamed and frantically ran for cover. The four cars are then seen slowly driving away.
Ahmad Fawzi, a spokesman for Syria's special envoy Kofi Annan, confirmed the observers were caught up in the country's violence as they met with the rebel Free Syrian Army.
"The U.N. Mission in Syria reports that shortly after 2 p.m. local time today, a [U.N.] convoy of four vehicles was struck by an explosion from an improvised explosive device," Fawzi said in a statement. "Three U.N. vehicles were damaged. No U.N. personnel were injured."