Border Patrol Agent Brian Terry was shot and killed Tuesday night along the Southern border of Arizona, CNN reports.

Terry was with three other Border Patrol agents when they got into a shoot-out with people who prey on migrants as they cross the border last night, NPR reports. None of the other officers were injured. Four suspects are in custody and authorities are looking for a fifth. The FBI is currently investigating the incident.

"Although we needed no reminder of the ever-increasing dangers along our southern border, this tragedy serves as stark notice that the threats facing all who serve in protecting our state and nation are real and are increasing on a daily basis," Arizona Gov. Jan Brewer told NPR.

Brewer rose to national notoriety after signing SB 1070 into law earlier this year. She has since demanded the federal government send more resources to the state to police the border, even though statistics have shown that border violence is actually on the decline.

"This is a sign that the politicians and bureaucrats are overly optimistic in their assessment that the borders are more secure now than at any point in our history," said National Border Patrol Council president T. J. Bonner, reported NPR. "It showed just the opposite."

"Border communities across the board are mourning the death of Agent Terry," said Jennifer Allen, the executive director of the Border Action Network, but cautioned against thinking about the border in such a narrow lens, as a dynamic between a besieged nation trying to defend against foreign threats. "Everyone mourns the loss of anyone’s life that is needlessly lost as a consequence of really bad policies. Unfortunately the impacts of our failed immigration and border policies hit our entire country hard, including the federal agents who police the border."

Allen said that increased U.S. policing and enforcement at the border in the last decade had funneled both migrants and smugglers into more remote border paths, and that criminal networks had predictably become more professionalized. "Unfortunately the violence of bandits and the increased intensity and risk of violence from drug smugglers and organized criminal networks has been entirely predictable and the Department of Homeland Security should not be surprised by it," Allen said.

"We’ve seen unfortunately too many times these tragedies on the border used to justify what results in even more mistakes and tragedies," Allen said, adding that what was needed was a thoughtful re-examination of our border policies instead of calls for more border security.

DHS Secretary Janet Napolitano responded to last night’s shooting with a renewed call for a stronger commitment to border enforcement while authorities investigated Terry’s death. "We are working with other federal, state and local authorities to ensure those responsible for this horrendous act are held responsible," Napolitano said. "We will leave no stone unturned as we seek justice for the perpetrators."

"We will honor his memory by remaining resolute and committed to the serious task of securing our nation’s borders."

Terry was 40 years old, and left behind his parents, a brother and two sisters.