U.S. Border Patrol agents have discovered a cache of several high-powered weapons along the Rio Grande river including a rocket launcher, assault rifles and plastic explosives, authorities said. Agents found the weapons on Tuesday in a black bag along a quiet stretch of the Rio Grande near Fronton, a small community about 210 miles south of San Antonio. No arrests have been made. “These deadly weapons could have had a devastating impact on communities on both sides of the border and to our agents and other law enforcement officers,” Rosendo Hinojosa, head of Border Patrol’s Rio Grande Valley sector, said...