A gunman opened fire during a protest on the Ethiopian Embassy grounds on Monday, according to a video of the incident, but no injuries were reported.
A spokesman for the U.S. Secret Service said it had detained a possible shooter after a report at about 12:15 p.m. EDT (1615 GMT) that shots were fired near the embassy in northwest Washington, D.C.
Witnesses said the gunfire took place inside the embassy compound during a protest against the Horn of Africa nation's government.
"About half a block from the embassy, I heard at least four shots, and I thought there were people killed," demonstrator Tesfa Simagne told Reuters Television.
A video taken inside the embassy gates and carried by the website of Ethiopian Satellite Television shows a man wearing a dark suit and brandishing a silver handgun. He points the weapon at others who argue with him and fires a single shot. Still waving the gun and arguing with protesters, the man backs up to an embassy door and goes inside.
A separate video made by a protester and provided to Reuters showed a bullet hole in the windshield of a car protesters said was outside the embassy gates.
A State Department official, who spoke on condition of anonymity, also said that no one was hurt. The person believed to have fired the shots turned himself in to authorities, and no arrests were made because he has diplomatic immunity, the official said.
Repeated phone calls to the embassy went unanswered.