This video was posted on YouTube by Syrian activists on April 18, it shows anti-government protesters in a Damascus suburb surrounding UN observers during their mission to monitor a fragile ceasefire in the country.
A crowd of people chanting: "May God support the Free Syrian Army" (referring to the group of armed opposition fighters and defectors from the Syrian army), swarmed the cars before the sound of an explosion sent them running for safety.
It is not clear what caused the blast. Demonstrators took shelter behind the UN vehicles just before they sped off.
[This video has not been independently verified.]