(Adds amateur video of two U.N. vehicles leaving demo)
BEIRUT, April 18 (Reuters) - Shooting broke out on Wednesday in a Syrian town during a visit by United Nations monitors, Syrian state media and activists said.
Activist amateur video footage, allegedly filmed in Erbin in Damascus province, showed two white cars with U.N. markings surrounded by anti-Assad protesters.
There is a loud bang, the protesters flee, and the camera moves to show dust rising in front of the first car before the sound of sirens as the white vehicles speed away.
Ikhbariya television channel said a "terrorist group" had also planted a bomb at a checkpoint, wounding a member of the Syrian security forces.
Another Internet video which activists said was filmed in Erbin showed a crowd of people running down a street with the sound of automatic weapons fire in the background.
There are as yet only half a dozen U.N. monitors in Syria, led by Moroccan Colonel Ahmet Himmiche. On Tuesday, they made a trip south to the city of Deraa apparently without incident.
On Wednesday they went to Erbin, on the outskirts of Damascus, escorted by Syrian police cars and were mobbed by flag-waving demonstrators protesting against President Bashar al-Assad.
A banner read: "The butcher continues killings, the observers continue observing, and the people continue with their revolution. We only bow to God."
Himmiche walked through the tight throng wearing a U.N. blue beret and flak-jacket and got into his vehicle where he spoke on a loud-hailer, apparently asking the crowd to move back and let the cars move out.