Mexican federal police captured a leading member of the Gulf drug cartel Friday at what appeared to have been his birthday party, authorities said.

Gilberto Barragan Balderas "is considered one of the main leaders of the Gulf Cartel" and is the subject of a $5 million reward by the U.S. Drug Enforcement Administration, said Ramon Pequeno, head of anti-drug operations for the federal police.

Barragan Balderas was allegedly in charge of the cartel's operations in Miguel Aleman, across the border from Roma, Texas. Police captured him at a party at a ranch near another border city, Reynosa, which is across from McAllen, Texas.

Police said the party was apparently in honor of Barragan Balderas' May 19 birthday. Two alleged associates were also arrested in the raid, which also netted an assault rifle and three pistols.

No formal charges had been filed against any of the suspects.

Barragan Balderas, 41, is wanted on drug trafficking charges in the United States under a 2008 indictment.

A DEA statement says he was "responsible for obtaining advanced notice regarding the movement and locations of military and state police patrols and mobile checkpoints, thus protecting shipments of cocaine and marijuana for the Gulf Cartel and Los Zetas" before the two gangs split in 2010.

The Gulf and Zetas cartels are now bitter rivals, and federal police said one of Barragan Balderas' "duties was to defend territory in Tamaulipas against attacks by the rival Zetas."

The Zetas have also been expanding into other territories in Mexico and engaging in a series of turf battles with gangs other than the Gulf.

On Friday, the attorney general of the north-central state of Zacatecas said at least 10 people were killed in a gunbattle apparently involving the Zetas and a rival front of gangs known as the "United Cartels."

"I say at least 10 people, because witnesses say that the gunmen, before they left ... took away other bodies," Attorney General Arturo Nahle told a local television station.

Gunmen left 11 vehicles at the scene of the confrontation in the remote town of Florencia de Benito Juarez. Six of the vehicles were bulletproofed, officials said.

The United Cartels is believed to be an alliance between the Gulf, Sinaloa and the La Familia cartels, to form a common front against encroachments by the Zetas.

Also Friday, Mexico's federal security spokesman said homicides in the Mexican border city of Ciudad Juarez have dropped from an average of 11 a day in October to about four a day in April.

Alejandro Poire attributed the drop to the deployment of thousands of federal police and efforts by local prosecutors. But he added that "the problem is not 100 percent solved."

More than 6,000 people have died the past two years from drug-related violence in the city, which sits across from El Paso, Texas.

Despite the bloodshed, the state legislature is scheduled to award the city the title of "Heroic" Ciudad Juarez on Saturday in recognition of the city's participation in the 1910-17 Mexican Revolution.

The killings extend throughout various parts of Mexico. On Friday, police in the Pacific coast state of Guerrero reported they found the decpitated bodies of four men in the township of Tecpan de Galeana, about 50 miles (80 kilometers) west of Acapulco.

Also Friday, President Felipe Calderon met with a delegation of U.S. lawmakers led by Rep. Connie Mack, a Florida Republican who is chairman of the House subcommittee on Western Hemisphere affairs.

Calderon's office said in a statement that the president stressed "the importance of combatting ever more firmly and efficiently weapons trafficking and money laundering," two elements that Mexico says fuel the bloody drug war that has cost over 35,000 lives since late 2006.

He also "stressed the importance of fully recognizing the contributions that Mexican migrants make to the U.S. economy and society."