Before the outbreak, the U.S. Border Patrol was responsible for detecting illegal immigration, terrorists and terrorist weapons from entering the United States, and prevent illegal trafficking of people and contraband.
It is unknown to what degree, if any, the border patrol was involved in maintaining order during the outbreak. It can be assumed that officers reported to their stations to control the border crossing. It can be implied that any officer who stayed at their post was overrun, considering that the main border crossing in California was positioned between San Diego and Tijuana - two heavily populated areas that were overrun.
At least three members of the Border Patrol were known to have survived the initial outbreak - Colton, the Unnamed Border Patrol Guard and the Second Unnamed Border Patrol Guard. All three were stationed at The Tunnel, which housed a bunker that they were making ready to occupy. One, the Unnamed Border Patrol Guard, died at the hands of Sierra, while Colton was severely injured.