Central American migrants traveling in a caravan broke through a Guatemalan border fence Friday, running into a wall of police in Mexico, whose government has promised the United States it will confront the caravan. Mexican television footage showed hundreds of migrants breaking through Guatemalan border posts and streaming onto a bridge connecting Mexico and Guatemala. The migrants were met on the other side by a line of Mexican police in riot gear. Witnesses say some of the migrants threw rocks and other objects at Mexican security forces, who used pepper spray to force the migrants to retreat.