Serb rioters broke into the US Embassy Thursday and set fire to an office after a large protest against Kosovo's independence. Masked attackers broke into the building, which has been closed this week, and tried to throw furniture from an office. A blaze broke out inside one of the offices. The neighboring Croatian Embassy also was attacked by the same group of protesters. Riot police drove armored jeeps down the street and fired tear gas to clear the crowd. US State Department spokesman Sean McCormack on Thursday urged the Serbian government to protect the US Embassy. He said the US ambassador was at his home and was in contact with US officials.