The United States pledged support for Mexico on Monday in its war against drug gangs as the FBI joined the investigation of the murders of two Americans and a Mexican linked to the U.S. consulate in Cuidad Juarez.
"The tragedy of this weekend just underscores how severe and significant a danger this represents to Mexico, to the United States, to the hemisphere," State Department spokesman P.J. Crowley told a news briefing.
"We all share that determination that ultimately, through a variety of means, we will take back these streets one community at a time."
U.S. President Barack Obama on Sunday voiced outrage over the murders, part of a surge in drug-related violence along the U.S.-Mexico border that has alarmed Washington.
An American employee of the consulate in Cuidad Juarez and her husband were shot dead by suspected drug gang hitmen as they left a consulate social event.
Crowley said the consulate in Cuidad Juarez would remain closed on Tuesday as officials reviewed security and that the Federal Bureau of Investigation had mobilized teams to assist Mexican authorities investigating the incident.
He downplayed suggestions that U.S. diplomats had been targeted in the attacks. Violence has exploded in recent months in Cuidad Juarez as rival drug gangs struggle for control over the city, a hotspot in Mexico's three-year-old drug war.
"This is something that has profoundly affected the Mexican population. At various times it has also affected U.S. citizens," Crowley said. "But as to whether this was a particular incident directed at U.S diplomats, I think we're not prepared to draw that conclusion yet."
The State Department on Sunday authorized the departure of dependents of U.S. government personnel from consulates in Ciudad Juarez and five other northern border cities.
Crowley said the United States would review security at its diplomatic facilities all along the border and work with Mexico to determine whether further steps were needed to protect them.
Nearly 19,000 people have been killed since President Felipe Calderon came to power in Mexico in late 2006 and launched a military assault on the drug cartels, leading to even more violence.
Most victims are rival traffickers and police and, to a lesser extent, soldiers, local officials and bystanders. It is rare for drug gang hitmen to target foreigners.
The United States has provided hundreds of millions of dollars to Mexico to help with the anti-drug fight, which Secretary of State Hillary Clinton last year acknowledged was fueled at least in part by U.S. demand for illegal drugs.