Pope Francis, who is usually calm and accommodating with his admirers, has clearly lost his temper with a person who pulled on him so hard he fell onto a child in a wheelchair.
Video footage showed the pontiff stopping to greet children while walking at the edge of a crowd in a stadium in Morelia, Mexico.
Two arms reached out to grab him and the person would not let go, even after the Pope lost his balance and his chest was pressing on the child's head.
Aides and security men stopped the Pope falling to the ground.
After he resumed an upright position, his face turned angry.
He looked at the person, raised his voice and said twice in Spanish: "Don't be selfish!"
It was not clear if the person who pulled the Pope was a man or a woman.
Francis, the first Latin American pope, is travelling to some of the poorest and most violent corners of Mexico on a six-day trip to bring a message of hope to millions of marginalised people.