CNN)Pope Francis was happily greeting children and pilgrims in St. Peter's Square on Tuesday when he slapped a woman's hand to free himself. The pope was making his way to the Nativity scene at the center of Vatican City. As he walked away from the crowd, a woman grabbed his hand and yanked him toward her, video shows. He became visibly upset and began slapping the woman's hand in an attempt to free himself from her grip, and he briefly shouted at the woman. Prior to the incident, the woman had made a sign of the cross. She addressed the 83-year-old pope as she took his hand but it's unclear what she was trying to tell him. CNN's Livia Borghese and Sugam Pokharel contributed to this report.