A Border Patrol agent shot and killed a suspected smuggler at a fence that separates the U.S. and Mexico after the agent felt threatened by the man, authorities said Thursday.

Mexico criticized what it described as an "excessive use of force" against immigrants and demanded an investigation.

Jose Alejandro Ortiz Castillo, a 23-year-old man who had been caught crossing the border 28 times since 1999, died in Mexico shortly after the Wednesday night shooting, Border Patrol spokesman Doug Mosier said.

An unidentified agent spotted Ortiz apparently leading two men and a woman through a hole in the border fence just east of downtown El Paso. Ortiz, who was carrying bolt cutters, picked up a rock as the agent was arresting the woman, Mosier said.

Mosier said the agent "felt threatened by the actions of the assailant who was holding a rock and bolt cutters."

The agent fired several shots, hitting Ortiz "multiple times," Mosier said. It was the agent's first fatal shooting.

Marco Antonio Torres Moreno — public safety director in Ciudad Juarez, the city across the river from El Paso — said Ortiz was shot once in the chest and once in the right forearm.

The Mexican government demanded in a statement that "all the weight of the law be brought to bear against the person or persons responsible."

"The Mexican government expresses a firm protest against the use of lethal weapons in the face of situations that do not represent a proportionate risk," the Foreign Relations Department said.

Ortiz had been deported from the U.S. in 2004, Mosier said.

Jesus Castillo, 43, Ortiz's brother, initially acknowledged that his brother had worked as an immigrant smuggler. But after speaking to investigators, he said his brother worked in construction and occasionally crossed the border to look for work in El Paso.

"The only thing I know is that they shot him head on, as if he were an animal, and neither Mexican nor American authorities had the courtesy to notify me about it until noon," Castillo said.

Wednesday night's shooting is the fifth fatal shooting involving Border Patrol agents in border states this year, federal officials said.