Yuma, AZ - Two teenagers from Guatemala fell off the 18-foot border wall while trying to illegally enter the United States, according to federal officials.It happened when the two teens and four other people scaled the border wall east of the San Luis Port of Entry in Arizona on Friday, Dec. 6, according to U.S. Customs and Border Protection.A 14-year-old girl and a 17-year-old girl fell off the wall, officials said. The 14-year-old, who was traveling with her mother, suffered a serious back injury, CBP said. The older teen, who was traveling without an adult, hurt an ankle.Border Patrol agents and medics responded to the scene to help the injured teens. Agents took the other four border-crossers into custody.