Mexican authorities on Friday announced the death of a man believed to be the No. 2 leader in the Gulf Cartel, saying the slaying appeared to have been the result of an internal power struggle.

Samuel Flores Borrego, 39, also known as “Metro 3,” was gunned down alongside a high-ranking police official from Diaz Ordaz known as Eloy Lerma Garcia, according to a statement from the Tamaulipas Attorney General’s Office. The statement mentions other violent attacks in the state, including the death of an infant, and goes on to offer condolences to all those affected.

Diaz Ordaz is across the border from Sullivan City.

Preliminary investigation of the incident that led to Flores death points to a power struggle within the Gulf Cartel, according to the Mexican army and the Mexico Attorney General’s Office (PGR). Official information sources identified Flores as the cartel boss responsible for overseeing operations in the Reynosa area.

The bodies of the two men were found early Friday inside a Ford Lobo pickup truck along the Monterrey-Reynosa highway, about 13 miles south of Reynosa, according to the state attorney general’s office.

Information from sources outside law enforcement indicated a firefight broke out among gunmen, prompting a response by federal authorities shortly thereafter. Another version of events held that Mexican federal police (SSP) or men disguised in the uniforms of SSP officers pursued Flores as he fled in the truck, resulting in a crash involving the pickup.

Neither account could be confirmed by official sources. However, a Mexican law enforcement official did verify that the bodies of both Flores and Lerma had several gunshot wounds, including wounds that appeared to be from the final kill shots.

Sources within and outside law enforcement confirmed that another vehicle involved in the altercation carried away two men who had been arrested and brought them to the Mexico Attorney General’s Office in Reynosa for questioning. A grenade was thrown about 7 a.m. Friday at the PGR building, causing minor damage to the structure but no injuries.

A news release the Mexican navy issued Thursday concerning a firefight in Apodaca, N.L., prompted confusion over Flores’ death due to the similarity between Flores’ nickname and that of a gunman involved in the Apodaca incident. The navy reported that 29-year-old Gustavo “M-3” Acosta Lujan had been killed in the Apodaca gun battle, leading some people in Reynosa and the Rio Grande Valley to believe Flores — whose aliases include “M Three” — was the one killed there.

Sources outside law enforcement described Flores as one of the older members of the Gulf Cartel, saying he began his career as a Tamaulipas law enforcement official before switching sides in the drug war. Lerma was described as a close acquaintance who served with Flores during his time in law enforcement.

Originally from Matamoros, Flores has been closely linked to the city of Reynosa and has worked there as plaza boss on and off over a period of many years. Most recently, he was in charge of coordinating certain Gulf Cartel operations in the state of Nuevo Leon, which added to the speculation that it was he rather than Acosta who had been killed Apodaca.

Authorities believe Flores was responsible for the death in early 2010 of Zeta lieutenant Sergio “Concord3” Peña Mendoza, a close associate of the Zetas’ No. 2 leader, Miguel Angel “El40” Treviño.

Widespread violence has dogged Tamaulipas and other states in northeast Mexico since the Gulf Cartel and the Zetas — a paramilitary organization that served as the enforcement arm of the Matamoros-based cartel — split in mid-February 2010.

After Peña’s slaying, the Zetas demanded Flores’ death and threatened open war with the Gulf Cartel if the score was not settled with his blood. The Gulf Cartel ignored the Zetas’ demand, and the internecine feud that erupted continues unabated to this day.

The Reynosa city morgue was under heavy guard Friday morning after Flores’ body was taken there, according to sources with firsthand knowledge of criminal activity.

The U.S. had offered a $5 million reward for his capture as a high-ranking member of the Gulf Cartel. He had been charged with various drug violations in a 2008 federal indictment in the District of Columbia.