A Canadian woman was shot dead and four other people were injured by a gunman on Monday at Mexico’s famed Teotihuacan archaeological site, authorities said.The gunman killed himself after opening fire at the popular tourist destination, home to pre-Aztecan pyramids, said Cristobal Castaneda, the security secretary for Mexico state, where the site is located.Videos on social media show the gunman firing periodic shots from halfway up the Pyramid of the Moon while tourists take cover behind...