Federal, state and local authorities conducted a massive sweep Thursday in the United States and Latin America of suspected Mexican drug cartel members in a widespread response to the killing of a U.S. agent in Mexico last week.

Carl Pike, assistant special agent in charge of the Drug Enforcement Administration’s special operations division, said the sweep is a direct reaction to the shooting death of Customs and Immigration Enforcement agent Jaime Zapata in Mexico last week.

“We are taking a stand and we are sending a message back to the cartels that we will not tolerate the murder of a U.S. agent, or any U.S. official,” Pike said.

An agent involved in a raid in Houston was shot and wounded Thursday, though the injury was not life-threatening, according to a federal official who spoke on condition of anonymity because the official was not authorized to discuss the ongoing operation. The shooting occurred during a raid by agents with the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives and Houston police. It was not clear what agency the injured officer worked for, and the suspected shooter is in custody.

Pike said the roundup, which began Wednesday and expected to continue into Friday, is targeting suspected criminals with ties to any Mexican drug cartel to try to disrupt drug trafficking operations in the United States.

“This is personal,” said Louie Garcia, deputy special agent in charge for Immigration and Customs Enforcement’s special operations unit. “We lost an agent, we lost a good agent. And we have to respond.”

The sweep, which is being mirrored this week in Brazil, El Salvador, Panama, Colombia, and Mexico, is being coordinated by DEA and ICE.

By Thursday morning, thousands of law enforcement officers in areas including Atlanta, St. Louis, Denver, Detroit, San Antonio, San Diego, Chicago, Newark and Miami had seized more than $4.5 million in cash and nearly 20 guns, arrested more than 100 people and confiscated about 23 pounds of methamphetamine, 107 kilograms of cocaine, 5 pounds of heroin and 300 pounds of marijuana at several hundred locations.

Zapata was killed and fellow ICE agent Victor Avila was wounded in Mexico on Feb. 15 when the Chevy Suburban they were in was run off the road by at least two vehicles loaded with armed men. Authorities have said the agents, who were driving in a fortified sport utility vehicle with diplomatic license plates, identified themselves as U.S. diplomats in the moments before the shooting.

Mexican authorities have arrested one person in connection with the brazen attack, which is believed to be the work of members of Mexico’s Zetas gang. Former Mexican special forces soldiers are among its members.

“We are basically going out to disrupt narcotics distribution here in the United States no matter what cartel their allegiance is to,” Pike said. “It would be futile to send a message back to one cartel when they all are just as guilty.”

Pike said that while the sweeps are a direct response to Zapata’s killing, the majority of suspects were already targets of other investigations.

“People actually sacrificed a great deal of work” for these sweeps, Pike said. “For the lost agent’s memory it’s important, but we’re also in a bully situation. If we don’t push back, some other 18-year-old cartel member is going to think, ‘They didn’t do anything, so all U.S. citizens are fair game.’”

Mexican law enforcement and politicians have become routine targets of Mexico’s warring drug cartels. For the most part, U.S. authorities had largely been avoided.

Last year, an employee at the U.S. consulate and her husband, a Texas jail guard, were killed on their way back to El Paso, Texas, from a birthday party in neighboring Ciudad Juarez, but Zapata’s killing marks the highest profile attack on U.S. authorities in Mexico since the 1985 kidnapping and killing of DEA agent Enrique “Kiki” Camarena.

This week, Mexican President Felipe Calderon complained that U.S. help in the fight against warring cartels has been “insufficient.” He made the comment to a Mexican newspaper in response to recently disclosed secret diplomatic cables in which U.S. officials criticized his anti-drug strategy. Calderon told the newspaper that the dispatches show U.S. diplomats’ ignorance about Mexican security efforts.

More than 35,000 people have been killed since Calderon launched a crackdown against drug gangs in December 2006.

Mexican authorities are leading the investigation of Zapata’s death and the Justice Department has announced a joint task force, led by the FBI, with the Homeland Security Department.

The Drug Enforcement Administration coordinated the sweep along with Immigration and Customs Enforcement.