Nazi swastikas and the name of the Islamist movement Hamas were spray-painted in red on the entrance to a Jewish synagogue in Miami Beach, local media reported Monday.
The vandalism, which authorities were investigating as a probable "hate crime," was discovered by a neighborhood watch patrol where the Torah V'Emunah synagogue is located.
Yona Lunger, a volunteer patrol member, said she did a double-take when she came upon the graffiti.
"I saw this and then I stopped and I said, 'Wait a minute. What am I seeing here?' and then I backed up again and I looked again and I immediately sent a text to the two supervisors," she told Miami's Channel 7 news.
Television images showed swastikas and the name "Hamas" spray-painted on the synagogue's columns.
The incident followed another on Saturday in which a Miami Beach family found their cars covered in eggs and the words "Hamas" and "Jew" written on the windows.
"I mean, honestly, it makes you question if it's safe to walk around wearing your yarmulke, like how safe you really are in America," said Josh Rosenberg, one of the family's neighbors.
Anti-Semitism in the US and worldwide has skyrocketed since Operation Protective Edge, Israel's self-defense operation in Gaza, began 21 days ago.
News of an increase in anti-Semitic violence follows a shocking Anti-Defamation League (ADL) report earlier this year, whereby more than 25% of the world's population was shown to hold anti-Semitic views.