MEXICO CITY -- The Mexican army killed the leader of the Jalisco New Generation Cartel, Nemesio Rubén Oseguera Cervantes, "El Mencho," on Sunday, decapitating what had become Mexico's most powerful drug cartel and thrusting swaths of the nation into chaos.

The drug lord was the Mexican government's biggest prize yet to show the Trump administration in its efforts to crack down on the cartels, and his death was met with a forceful reaction from the cartel, known by its Spanish initials CJNG.

Cars burned out by cartel members blocked roads at more than 250 points in 20 Mexican states, authorities said, and left smoke billowing into the air. Jalisco's capital, Guadalajara, was turned into a ghost town Sunday night as civilians hunkered down. School was canceled on Monday in several states. Authorities in Jalisco, Michoacan and Guanajuato reported at least 14 dead, including seven National Guard troops.

Oseguera Cervantes was wounded in an operation to capture him on Sunday in Tapalpa, Jalisco -- about a two-hour drive southwest of Guadalajara -- and he died while being flown to Mexico City, the Defense Department said in a statement. The state is the base of the cartel known for trafficking huge quantities of fentanyl and other drugs to the United States.

Cartel a major fentanyl trafficker
During the operation, troops came under fire and killed four people at the location. Three more people, including Oseguera Cervantes, were wounded and later died, the statement said. Two others were arrested, and armored vehicles, rocket launchers and other arms were seized. Three members of the armed forces were wounded and are receiving medical treatment.

A Jalisco state official who requested anonymity because they were not authorized to speak publicly said a member of the National Guard died in Tapalpa during the operation, six other National Guard members died in Zapopan beside Guadalajara, a jail guard was killed at a lockup in Puerto Vallarta when prisoners rioted, and an agent from the Jalisco state prosecutor's office was killed in Guadalajara. Details were not immediately available.

White House Press Secretary Karoline Leavitt said via X that the U.S. government provided intelligence support for the operation.

"'El Mencho' was a top target for the Mexican and United States government as one of the top traffickers of fentanyl into our homeland," she wrote. She commended Mexico's military for its work.

"Ever since President (Claudia) Sheinbaum has been in power, the army has been way more confrontational, combative against criminal groups in Mexico," said David Mora, analyst for International Crisis Group in Mexico. "This is signaling to the U.S. that if we keep cooperating, sharing intelligence, Mexico can do it, we don't need U.S. troops on Mexican soil."

Roadblocks and burning vehicles
The killing of the drug lord set off several hours of roadblocks with burning vehicles, tactics commonly used by the cartels to block military operations. Videos circulating on social media showed smoke billowing over the tourist city of Puerto Vallarta in Jalisco, and people sprinting through the airport of the state's capital in panic.

Air Canada announced it was suspending flights to Puerto Vallarta "due to an ongoing security situation" and advised customers not to go to their airport. A number of Mexican and international airlines also canceled flights.

In Guadalajara, burning vehicles blocked roads and businesses shuttered just months before Mexico's second-largest city is scheduled to host matches during this summer's soccer World Cup.

The U.S. State Department warned U.S. citizens in Jalisco, Tamaulipas, Michoacan, Guerrero and Nuevo Leon states to remain in safe places due to the security operations. Canada's embassy in Mexico warned its citizens in Puerto Vallarta to shelter in place and generally to keep a low profile in Jalisco.

Jalisco Gov. Pablo Lemus told residents to stay at home, suspended public transportation and said that the state was "living through critical hours."

The U.S. Embassy issued a statement on Sunday telling Americans in Puerto Vallarta to shelter in place.

"Due to ongoing, widespread security operations and related road blockages and criminal activity in many areas of Mexico, U.S. citizens should shelter in place until further notice. Roadblocks have impacted airline operations, with some domestic & int'l flights canceled in both Guadalajara & Puerto Vallarta. Taxis/ride shares are suspended in Puerto Vallarta. Seek shelter and remain in residences or hotels."

US had offered up to $15 million for his capture
The U.S. State Department had offered a reward of up to $15 million for information leading to the arrest of El Mencho. The Jalisco New Generation Cartel is one of the most powerful and fastest-growing criminal organizations in Mexico, and began operating around 2009.

In February 2025, the Trump administration designated the cartel as a foreign terrorist organization.

Sheinbaum has criticized the "kingpin" strategy of previous administrations that took out cartel leaders only to trigger explosions of violence as cartels fractured. While she has remained popular in Mexico, security is a persistent concern, and since U.S. President Donald Trump took office a year ago, she has been under tremendous pressure to show results against drug trafficking.

On Sunday, Sheinbaum applauded Mexican security forces and called for calm in a post on X.

Known as an aggressive cartel
The Jalisco cartel has been one of the most aggressive cartels in its attacks on the military - including on helicopters - and is a pioneer in launching explosives from drones and installing mines. In 2020, it carried out a spectacular assassination attempt with grenades and high-powered rifles in the heart 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 infamous criminal groups, with a presence in all 50 U.S. states. It is one of the main suppliers of cocaine to the U.S. market and, like the Sinaloa cartel, earns billions from the production of fentanyl and methamphetamines. Sinaloa, however, has been weakened by infighting after the loss of its leaders, Ismael "El Mayo" Zambada and Joaquín "El Chapo" Guzmán, both in U.S. custody.

Oseguera Cervantes, 59, was originally from Aguililla in the neighboring state of Michoacan. He had been significantly involved in drug trafficking activities since the 1990s. When he was younger, he migrated to the U.S., where he was convicted of conspiracy to distribute heroin in the U.S. District Court for the Northern District of California in 1994 and served nearly three years in prison.

Following his release from custody, Oseguera Cervantes returned to Mexico and reengaged in drug trafficking activity with drug lord Ignacio Coronel Villarreal, alias "Nacho Coronel." After Villarreal's death, Oseguera Cervantes and Erik Valencia Salazar, alias "El 85," created the Jalisco New Generation Cartel around 2007.

Initially, they worked for the Sinaloa Cartel, but eventually split, and for years, the two cartels have battled for territory across Mexico.

Indicted several times in the United States
Since 2017, Oseguera Cervantes has been indicted several times in the United States District Court for the District of Columbia.

The most recent superseding indictment, filed on April 5, 2022, charges Oseguera Cervantes with conspiracy and distribution of controlled substances (methamphetamine, cocaine, and fentanyl) for the purpose of illegal importation into the United States and use of firearms during and in connection with drug trafficking offenses. Oseguera Cervantes is also charged under the Drug Kingpin Enforcement Act for directing a continuing criminal enterprise.

Last year, people searching for missing relatives found piles of shoes and other clothing, as well as bone fragments at what authorities later said was a Jalisco cartel recruitment and training site.