The adorable youngster, who told police his name was Amir, didn't say much else. He speaks Farsi, the language spoken in Iran, and very little German, the police said.
Amir's smiling face was featured in many newspapers and on television stations, with pleas from the police for any information regarding the child.
Police said they arrested a woman and a man on Friday evening. They were reportedly the last people seen with the child. But authorities still don't know where the child came from or why he was left alone.
Additional details about the two arrested were not available.
Authorities are not sure of Amir's age, though suspect he is between two and three. He has been living with a foster family since being picked up in front of the fast food chain last Saturday.