Two U.S. National Guard members and a Border Patrol agent were killed and a fourth person was injured when a helicopter went down near Rio Grande City, Texas, on Friday, officials said. The UH-72 Lakota helicopter crashed around 2:50 p.m. local time while it was “conducting aviation operations” in the area, according to a statement from the Defense Department’s Joint Task Force North. The helicopter had been assigned to a support mission at the Southwest border of the U.S., the statement said. Personnel move towards a crashed UH-72 Lakota helicopter near Rio Grande City, Texas, on…