The U.N.'s observer mission in Syria was caught up in a burst of violence Tuesday captured on video, with a roadside bomb damaging its cars just minutes after witnesses said government forces gunned down mourners at a funeral procession nearby. The mission confirmed its vehicles were hit by a bomb shortly after they met with Syrian rebels, and said there were no injuries. It was not clear how close the observers were to the funeral shootings, but if confirmed, a government attack on civilians directly in front of the observer mission could put pressure on them to describe publicly what they are seeing in Syria. They report back to the United Nations but have not publicized their findings. 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 latest bomb attack was posted by activists online. Just minutes earlier, Syrian forces fired on a funeral procession, activists said. Fadi Al-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, some of them in serious condition. It was impossible to independently confirm the toll. The Syrian uprising began in March 2011 with mostly peaceful protests calling for change, but a relentless government crackdown led many in the opposition to take up arms. Some soldiers also have switched sides and joined forces with the rebels.