Two Suspected Bandits Slain by Border Patrol : Shooting: Authorities say a group of suspected thieves surrounded the officers, possibly mistaking them for potential victims in the darkness.

Four U.S. Border Patrol agents opened fire on a group of alleged thieves late Thursday, killing two of them, after the assailants surrounded the officers and appeared poised to attack, according to official accounts released Friday. The agents were in uniform and armed.

The two dead men, who had not been identified Friday evening, were slain in Border Field State Park near Imperial Beach, at a surf-side spot about a quarter of a mile north of the border. At least two others in the group fled into Mexico, officials said.

Authorities said one of the attackers brandished what appeared to be a pistol, but officials found only a replica of a weapon and a kitchen knife at the scene.

Whether the assailants intended to rob the officers or to harm them remained unknown, as authorities released only limited details about the shootings. In similar border shootings, U.S. officials have said that the suspects sought to rob the lawmen, mistaking them in the dark for undocumented immigrants.

“I cannot explain why these individuals (the suspected thieves) did what they did,” said Ben Davidian, Los Angeles-based regional commissioner for the U.S. Immigration and Naturalization Service, parent agency of the Border Patrol.

Davidian, the only INS official who provided any concrete information about the shooting, gave little beyond a terse statement. His behavior is in line with a new INS media policy, outlined last month by INS Commissioner Gene McNary, that restricts comments by regional personnel on a range of issues without approval from Washington.

Thursday’s shootings are being investigated by the San Diego County Sheriff’s Department in conjunction with the FBI, which has authority because federal officers were involved.

The incident comes just three weeks after a new San Diego Police Department anti-crime border patrol unit shot a screwdriver-wielding undocumented immigrant, who survived. But it seemed likely to revive the controversy surrounding law enforcement tactics in the border zone.

The region is annually traversed by hundreds of thousands of undocumented people en route to jobs and family in the United States.

“I really got a problem with this toy gun stuff,” said Roberto Martinez, a rights activist affiliated with the American Friends Service Committee, the social action arm of the Quaker Church. “I just can’t believe that these guys attack armed Border Patrol agents with a toy gun.”

In past incidents, officials have said that the darkness of the border area at night makes it difficult for thieves to recognize uniformed lawmen, thus explaining a seemingly suicidal propensity to attack armed officers, occasionally with nothing more than fake guns or crude knives.

Thursday’s incident appeared to be the first fatal shooting of suspected border robbers by U.S. authorities in San Diego since Jan. 4, when members of a controversial anti-crime patrol consisting of U.S. Border Patrol agents and San Diego police shot and killed two men who also reportedly were poised to attack armed lawmen. That incident, just two weeks after the same squad killed two other suspected thieves, triggered a furor and led to the disbanding of the joint anti-crime unit, which had been in existence for five years, during which it killed 18 suspects.

The shootings Thursday occurred in an area where authorities have lately noticed an increased amount of thievery, according to the INS.

Before the slayings, the INS said, the Border Patrol had arrested eight suspected undocumented immigrants in the area who reported that they had just been robbed by thieves carrying knives and a gun. The site is just north of Tijuana’s huge Bullring by the Sea.

U.S. and sheriff’s authorities refused to release the names of the four Border Patrol officers involved in the shooting. None of the agents was injured.

The Sheriff’s Department provided the following account of the slayings:

About 8:30 p.m. Thursday, the four agents were patrolling the Pacific shoreline, walking north along the beach, within a quarter of a mile of the international line, when a man ran in front of them and blocked their path. He made a “sweeping” move with his right hand and revealed what agents believed was a handgun, which he pointed at the agents.

At the same time, at least three other men ran toward the agents from behind, surrounding the officers. One of the men was yelling profanities in Spanish and brandishing a large knife.

Facing such a threat, authorities said, the agents opened fire with their service revolvers. Two suspects died at the scene; the others fled on foot to the south.

The assailants’ behavior and physical characteristics closely matched those of thieves known to be operating in the area, according to the Sheriff’s Department.

The results of the investigations by the sheriff and the FBI will be turned over to the U.S. attorney’s office for review.

It was unclear whether the Border Patrol would conduct an internal review of the incident, as has been routine in former shootings by border agents.

A Border Patrol spokesman in San Diego declined to comment on the shootings Friday, referring all questions to the INS regional office in Los Angeles, in line with the new media policy launched by INS Commissioner McNary in Washington. Davidian, the INS commissioner in Los Angeles, declined to say much beyond his prepared statement.