海角大神

A U.S.聽Border Patrol agent was shot dead and another wounded when they came under fire on Tuesday while responding to a tripped ground sensor in a drug smuggling corridor in聽Arizona聽near the border聽with聽Mexico, authorities said.

Authorities said three agents were on foot about 5 miles (8 km) north of the聽border in rocky terrain when gunfire erupted well before daybreak, but provided few additional details on the circumstances of the violence.

"As they were walking up the trail, they reported taking gunfire," Cochise County Sheriff's spokeswoman聽Carol Capas聽said. "We have unknown suspect or suspects at this point."

The shooting marked the fourth conflict-related death of a聽Border Patrol agent in聽Arizona聽in less than two years and reignited concerns about聽border security in a state that is already at the forefront of the national immigration debate.

"Flags will be lowered in honor of the slain agent. Elected officials will vow to find those responsible. Arizonans and Americans will grieve, and they should. But this ought not only be a day of tears," Republican Governor聽Jan Brewer聽said in a statement.

"There should be anger, too. Righteous anger - at the kind of evil that causes sorrow this deep, and at the federal failure and political stalemate that has left our border聽unsecured and our聽Border Patrol in harm's way," added Brewer, a vocal foe of President聽Barack Obama's administration聽on immigration.

Brewer, citing what she described as a federal failure to secure聽Arizona's southern border, signed a broad immigration crackdown into law in 2010 to try to crack down on the flow of illegal immigrants into the state where an estimated 360,000 undocumented people live.

Critics of the law, which includes a requirement that police check the immigration status of anyone they stop and suspect of being in the country illegally, have said it could lead to racial profiling.

Ground sensors聽

The shooting took place near the聽border town of Naco, southeast of聽Tucson, which remains a corridor for smuggling marijuana and people, despite the construction of a tall, steel fence along the border.

"We need to redouble our efforts to secure the聽border and ensure the safety of聽Border Patrol agents," U.S. Democratic Representative Ron Barber, who represents the聽southern Arizona聽district where the shooting occurred, said in a statement.

Sheriff's deputies were called to the scene at 1:33 a.m. local time (4:33 a.m. EDT/0833 GMT) and found one agent dead and another with non-life-threatening injuries, Capas said. A third was unharmed. FBI agents were also investigating.

Across the聽border from Naco in a Mexican town of the same name,聽Mexican police聽said a team of soldiers and federal and local police was searching for a suspect or suspects in the case. "We have no information about anybody being detained," said a聽Naco police聽officer who declined to be named.

The聽Border Patrol identified the slain agent as Nicholas Ivie, 30, who was originally from聽Utah聽and had worked for the agency since 2008.

The agents had been responding to a sensor, which picks up on movement or vibrations in areas authorities suspect are used by drug traffickers and illegal immigrants. When an alert is triggered, agents have the option to respond.

Capas said the agents who were shot were assigned to the聽Brian A. Terry聽Border Patrol Station, named after an agent whose 2010 death in the line of duty in聽Arizona聽borderlands was linked to a botched U.S. operation to track guns smuggled to聽Mexico.

In that case, two guns tracked by the Bureau of Alcohol, Tobacco, Firearms and Explosives in the "Fast and Furious" sting operation, which let weapons slip into聽Mexico, were retrieved from the spot where Terry died in a shoot-out with bandits. It was unclear if the weapons were used in his murder.

Two聽Border Patrol agents were killed last year in an accident during a car chase with smugglers near聽Phoenix.

(Additional reporting by David Schwartz in聽Phoenix, Tim Gaynor and Lizbeth Diaz in聽Mexico聽City, and Daniel Trotta in New York; writing by Cynthia Johnston; wditing by Stacey Joyce and Mohammad Zargham)