The man who brought down the Texas elementary school shooter on Tuesday was a US Border Patrol agent who rushed in  without backup and killed the assailant.

18 children were killed along with a teacher when the suspected gunman, 18-year-old Salvador Ramos, entered the school and began shooting - only to be taken out by the agent.

"A Border Patrol agent who was nearby when the shooting began rushed into the school without waiting for backup and shot and killed the gunman, who was behind a barricade," reported the Associated Press. "The agent was wounded but able to walk out of the school."

As FoxLA's Bill Melugin reported on Tuesday, "an elite BORTAC Border Patrol agent is believed to have shot and killed the gunman at Robb Elementary School today."