A German man has tried to jump into Benedict XVI's popemobile during his weekly general audience held in St Peter's Square at the Vatican.
The 27-year-old man was wrestled to the ground by security officers.
The Pope, himself German, was not injured and did not seem to notice the incident. He proceeded with the audience as normal.
In 1981, Benedict's predecessor John Paul II was shot by Turkish gunman Ali Agca as he drove around the square.
The man who tried to jump into the popemobile on Wednesday had been standing among some 35,000 people who were attending the audience.
He leaped over the metal barriers separating the crowd from the pontiff and landed behind the moving vehicle.
Several security guards grabbed the man, who was wearing a pink T-shirt, black shorts and a baseball cap.
He seemed to be trying to climb onto the Pope's vehicle, an open jeep, as the pontiff was driven around the square greeting pilgrims, says the BBC's David Willey in Rome.
The man was later questioned by Vatican police before being taken to hospital to be assessed in a psychiatric ward.
Vatican spokesman Federico Lombardi described the man as a "mentally unstable".
"His aim was not an attempt on the Pope's life, but to attract attention to himself," Mr Lombardi said.