A Republican lawmaker from Texas called the slaying of a federal agent in Mexico a “game changer” and is pushing for the U.S. to “respond forcefully.”

Gunman launched an attack on two agents with the Immigration and Customs Enforcement (ICE) on Tuesday as the men drove through Mexico on routine business.

Rep. Michael McCaul said on Wednesday that it “was an intentional ambush” and that the two men - special agent Jaime Zapata, who died, and special agent Victor Avila, who was wounded – had their vehicle with diplomatic license plates run off the road by members of a drug cartel.

“When the agents identified themselves as American diplomats, the cartel members responded by opening fire on the officers,” said McCaul in a statement.

“This tragic event is a game changer. The United States will not tolerate acts of violence against its citizens or law enforcement and I believe we must respond forcefully. This should be a long overdue wakeup call for the Obama administration that there is a war on our nation's doorstep."

The last targeted killing of a U.S. agent in the line of duty in Mexico was in 1985, when Drug Enforcement Agent Enrique "Kiki" Camarena was tortured and murdered by drug traffickers. Mexican President Felipe Calderon declared war on the drug cartels four years ago. Since then, more than 30,000 people have been killed in the country. Federal and local law enforcement statistics in the U.S., however, show that violent crime has decreased in the major U.S. cities along the southern border.

McCaul’s comments come as the Departments of Homeland Security (DHS) and Justice (DOJ) announced on Wednesday the creation of a joint task force, “which will be led by the Federal Bureau of Investigation and will leverage the investigative capabilities of both agencies to work with Mexico in tracking down the perpetrators and swiftly bring them to justice.”