Violent clashes broke out in parts of western Mexico on Sunday during a military operation that left a Jalisco New Generation cartel leader dead, sparking widespread security concerns across the region.

Mexican security forces killed Nemesio Ruben Oseguera Cervantes, also known as “El Mencho,” during an operation by Mexico’s defence ministry in the western state of Jalisco. A statement on X said he was wounded during a raid on the city of Tapalpa and died while being transported to Mexico City.

The state of Jalisco is the base for a cartel known for smuggling large amounts of fentanyl and other drugs into the United States.

US Deputy Secretary of State Christopher Landau confirmed that the cartel leader, following his death, was described as “one of the bloodiest and most brutal drug lords”.

“This is a wonderful development for Mexico.

This is a wonderful development for Mexico, the US, Latin America, and the world. Good people are stronger than evil people,” he said on X.

A US defence official told CBS News that the US military played a role in the operation through the Joint Interagency Task Force-Counter Cartels, which regularly works with the Mexican military through the US Northern Command. The officer emphasised that “this was a Mexican military operation, so the success is theirs.”

Mike Vigil, former head of DEA international operations, told CBS News that the military operation was “one of the most significant actions taken in the history of drug trafficking.”

“He added that we are talking about someone who is almost at the same level as (Joaquin) ‘El Chapo’ Guzman and (Ismael) ‘El Mayo’ Zambada.” “(Oseguera Cervantes) is one of the greatest drug capos in the history of worldwide drug trafficking.”

During the operation, soldiers were fired upon and four people were killed at that location. Three more people, including Oseguera Cervantes, were injured and later died, the Defence Ministry statement said. Two others were arrested, and armoured vehicles, rocket launchers, and other weapons were seized. Three members of the armed forces were injured and are undergoing treatment.

The killing of the powerful drug lord led to roadblocks for several hours with vehicles being burnt in Jalisco and other states. Cartels commonly use such tactics to thwart military operations.

In response to the clashes, Jalisco Governor Pablo Lemus Navarro activated “Code Red,” a protocol for a state of emergency or security crisis. In a post on Twitter, he said public transportation has been suspended throughout Jalisco and urged people in the region to stay in their homes until the situation is under control.

Mexican President Claudia Sheinbaum Pardo on social media Acknowledged the disruptions but insisted, “In the vast majority of the national territory, activities are proceeding entirely as normal.”

Videos circulating on social media showed clouds of smoke billowing over the city of Puerto Vallarta, a major city in Jalisco, and panic circling at the state capital’s airport.

“They’re burning buses, they’re blocking roads, not only in Jalisco, but also in Michoacán, Colima, Tamaulipas, Guanajuato and Aguas Calientes,” Vigil said. “They aim to demonstrate their continued strength and resilience, demonstrating that this incident did not devastate them,” Vigil said.

Burning vehicles blocked roads in Guadalajara, the capital of Jalisco and Mexico’s second-largest city, which is scheduled to host World Cup matches this summer.

Sources on the ground and family members in the city told CBS News’ Nidia Cavazos that a similar situation unfolded at the airport in the Mexican border city of Reynosa in Tamaulipas state. He said that cartel members have blocked the roads leading to the airport. Reynosa, which borders McAllen, Texas, typically hosts a high volume of American travellers. Major access roads to the international bridges remained blocked, despite the bridges remaining open.

The US State Department has issued a security alert to give advice to US citizens in several Mexican states, including Jalisco, Tamaulipas, Michoacán, Guerrero, and Nuevo León. They will be sheltered in place until further notice.

Air Canada temporarily suspended operations at Puerto Vallarta Airport due to what it described as “the ongoing security situation in Puerto Vallarta” affecting the airport.

“We are monitoring the situation and are in contact with local authorities who are working to resolve the issue,” the airline said. Said.

Southwest and Alaska Airlines confirmed they had cancelled flights to and from Puerto Vallarta on Sunday, while Delta Airlines issued travel waivers to customers with flights in and out of the airport in Puerto Vallarta as well as Guadalajara.

“The safety of our customers and crew always comes first and we are closely monitoring the situation in the area. We have taken steps to adjust our operations accordingly and are working to communicate with our affected customers,” Delta said in a statement.

The Jalisco New Generation Cartel, known as CJNG, is one of the most powerful and fastest-growing criminal organisations in Mexico. Oseguera Cervantes, 59, is originally from Aguila, in the neighbouring state of Michoacán. He has been significantly involved in drug trafficking activities since the 1990s. He helped co-found the Jalisco New Generation Cartel with Eric Valencia Salazar, alias “El 85”, around 2007.

The Justice Department took Valencia Salazar, one of the 29 wanted cartel leaders, into US custody last February.

The Jalisco cartel has been one of the most aggressive cartels in its attacks on the military – including using helicopters – and is a leader in launching explosives from drones and planting mines. In 2020, a spectacular assassination attempt with grenades and high-powered rifles was carried out in the center of Mexico City against the then head of the capital’s police force and now federal security secretary.

The DEA considers the cartel to be as powerful as the Sinaloa Cartel, one of Mexico’s most notorious criminal groups, with a presence in all 50 US states.

The United States District Court for the District of Columbia has repeatedly convicted Oseguera Cervantes since 2017. The US State Department had offered a reward of up to $15 million for information leading to the arrest of El Mencho.

In February 2025, the Trump administration designated the cartel as a foreign terrorist organization, saying, “In addition to fentanyl trafficking, the group also engages in extortion, migrant smuggling, oil, and mineral theft, as well as arms trade.”