Washington (CNN) -- All four members of a Border Patrol team present when one of the agents was fatally shot last year were armed with lethal weapons, Homeland Security Secretary Janet Napolitano said Friday, refuting claims that some of the officers were armed only with "bean bag" guns.
On the night of his death, Agent Brian Terry carried a HK P2000 handgun and an M4 long rifle, and while some team members had "bean bag" guns, all also had lethal weapons, Napolitano said.
Members of Congress and others expressed alarm recently after an FBI affidavit noted that two of the Border Patrol officers fired non-lethal "bean bag" guns at their armed assailants. The affidavit led some people to conclude that some agents were armed only with the non-lethal weapons.
Critics also said members of the Border Patrol tactical unit were under orders to use "less-than-lethal" force.
But in a letter to Sen. Charles Grassley, R-Iowa, Napolitano said the officers were empowered to defend themselves and were equipped with a combination of lethal and non-lethal weapons. "At no point, however, are our law enforcement personnel ever performing their duties equipped with only a less-lethal device," Napolitano wrote.
In the FBI affidavit, Special Agent Scott Hunter said the Border Patrol agents, using thermal binoculars, spotted a group of "at least" five people believed to be illegal aliens around midnight in Peck Canyon near Rio Rico, Arizona. At least two of the people in the group were carrying rifles, the affidavit said.
As the group drew near, one of the agents identified himself as an officer and ordered the men to drop their weapons.
"When the suspected aliens did not drop their weapons, two Border Patrol Agents deployed 'less than lethal' bean bags at the suspected aliens," Hunter wrote. "At this time, at least one of the suspected aliens fired at the Border Patrol Agents," striking Terry, Hunter wrote.
Then two agents returned fire with a long gun and a pistol, striking one of the men in the group, Hunter wrote.
No one has been charged in the shooting, which authorities believe was done by Mexican bandits who were in the Arizona desert to prey on illegal border crossers.