Mexico City ? Mexican security forces killed reputed Gulf cartel leader Antonio Ezequiel Cardenas Guillen, one of Mexico’s most-wanted drug lords, in a spectacular, hours-long gunbattle Friday in the northern border city of Matamoros.

Cardenas Guillen, also known as “Tony Tormenta” or “Tony the Storm,” is the brother of imprisoned former leader Osiel Cardenas Guillen and is believed to have run the powerful cartel along with Jorge Eduardo Costilla Sanchez.

He is the latest in a growing number of high-profile cartel leaders who have been captured or killed by the armed forces since President Felipe Calderon stationed them across the country to battle drug traffickers.

The clashes across the border from Brownsville, Texas, also claimed the lives of three gunmen and two marines, said Alejandro Poire, Calderon’s security spokesman. A soldier and a local reporter were also killed, the Mexican Defense Department said in a news release.

Gunfire first broke out about 11 a.m. at an upscale residential area in Matamoros and shootouts ensued throughout the city after that for about eight hours, said a resident who asked not to be identified for fear of reprisal.

A video posted on YouTube shows a string of SUVs and pickup trucks racing through a street while continuous shooting is heard in the background. Men wearing ski masks get out of a car and use it to block the street.

Cardenas Guillen, 48, had been indicted in the United States on drug-trafficking charges and U.S. authorities had offered a $5 million reward for information leading to his arrest. Mexican authorities offered a $2 million reward and had him on their list of the nation’s most wanted drug traffickers.

His death is a blow to Mexico’s second-most powerful cartel and a major boost to Calderon’s war on drug cartels. Mexico’s Sinaloa cartel is considered Mexico’s largest drug cartel. U.S. authorities considered Cardenas Guillen a key trafficker of cocaine and marijuana into the United States.

“Today, we have taken another meaningful step toward the dismantling of criminal groups that do so much damage to our country,” Poire said.

The deceased trafficker’s brother Osiel Cardenas Guillen led the Gulf cartel until his arrest by Mexican authorities in 2003. Osiel was extradited to the United States in 2007 and sentenced to 25 years in prison by a Texas court in February.