The marines were on foot patrolling a rural area around the dusty outskirts of Progreso in northern Mexico, 80 miles west of the Texas border, when grenades were tossed at them out of a moving vehicle, prompting them to return fire.

One of the marines was injured in the initial blast, but not fatally. Two men in the vehicle were killed, one of them believed to be Heriberto Lazcano, the leader and founding member of the Zetas drug cartel, the Mexican navy reported.

“Information was obtained after the first forensics tests were carried out that yielded indications that suggest that one of the bodies is Heriberto Lazcano,” read a statement from the navy, the Associated Press reported.

“The Navy Department is coordinating efforts with Coahuila state, and will be awaiting the conclusions of the forensics examination in the case.”

If confirmed, the death of Lazcano will be considered a major victory for Mexican security forces against one of the country’s most powerful and notorious drug cartels.

Lazcano helped found the Zetas around the turn of the millennium after deserting with a group of operatives in the Mexican Army special forces.

Initially, the group had served as enforcers for the long-established Gulf cartel, carrying out assassinations and protecting drug shipments. In 2010, the Zetas turned on their former employers and established themselves as an independent drug trafficking organization.

Since the split, the Zetas have begun edging the Gulf cartel out of northeastern Mexico, a gang war that has resulted in hundreds of killings, displaying the Zetas’ signature brutality of placing decapitated heads on spikes and leaving rows of headless bodies by the roadside.

While Lazcano’s death would deal a symbolic blow to the Zetas, it would be unlikely to severely affect the cartel’s operations. There are reports that the Zetas' second-in-command Miguel Angel Trevino Morales had already been vying against Lazcano for leadership and became the de facto boss of the cartel around August, the AP reported.

Roughly 50,000 people have been killed since outgoing President Felipe Calderon began his military campaign against the drug cartels in 2006, the Los Angeles Times reported. The civilian population is often caught up in the violence as innocent bystanders and victims of extortion, and is often targeted by cartels for the purposes of intimidating others to remain silent on their criminal activities.

Calderon’s administration has claimed the majority of deaths comprise criminals in the drug trade, but fewer than 5 percent of the homicides have ever been investigated, according to political activist and author Tom Hayden in his article titled, Mexico's Election: A Vote for Peace, a Plan for War, for the Nation magazine.

Critics often point to Calderon’s “kingpin strategy” of targeting cartel bosses as being a major contributor to the surge in violence driven by infighting within cartels as new leaders emerge and an escalation of turf wars among the constant atmosphere of violence.

President-elect Enrique Pena-Nieto, due to take office in December, has said he intends to decrease the violence, though details have been vague.

He has indicated that he intends to recall the 50,000 military troops that have been deployed under Calderon and build up the national police force to focus less on engaging cartels in combat and commit to filling the security void left by corrupt local law enforcement.

Critics contend that the violence has already escalated to a point where the cartels will not cease their strategy of mass intimidation of the civilian population and confrontations will be unavoidable.