Schools have been shut in several Mexican states, and local and foreign governments alike warned their citizens to stay indoors, as widespread violence erupted following the army’s killing of the powerful leader of the Jalisco New Generation Cartel.

Nemesio Ruben Oseguera Cervantes, also known as “El Mencho”, was killed in a shootout in his home state of Jalisco on Sunday as the Mexican military attempted to capture him.

“El Mencho” was the boss of one of the fastest-growing criminal networks in Mexico, notorious for trafficking fentanyl, methamphetamine and cocaine to the United States and for staging brazen attacks against government officials who challenged it.

Cartel members responded with violence across the country, blocking roads and setting fire to vehicles.

The killing of “El Mencho” comes 10 years after his rival, Joaquin “El Chapo” Guzman, the leader of the Sinaloa Cartel, was captured in a joint US-Mexico operation. El Chapo was later extradited to the US.

President Claudia Sheinbaum urged calm, and authorities announced late on Sunday that they had cleared most of the more than 250 cartel roadblocks across 20 states. The White House confirmed that the US had provided intelligence support to the operation to capture the cartel leader and applauded Mexico’s army for taking down a man who was among the most wanted criminals in both countries.

The US Department of State had offered a reward of up to $15m for information leading to the arrest of “El Mencho”. The Jalisco New Generation Cartel is one of the most powerful and fastest-growing criminal organisations in Mexico, which began operating around 2009.

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In February 2025, the Trump administration designated the cartel a “Foreign Terrorist Organization”.

Sheinbaum has criticised 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 US President Donald Trump took office a year ago, she has been under intense pressure to show results against drug trafficking.

The Jalisco cartel has been one of the most aggressive in its attacks on the military, including on helicopters, and specialises in launching explosives from drones and planting mines.

In 2020, it carried out a dramatic assassination attempt with grenades and high-powered rifles in the heart of Mexico City against the then head of the capital’s police force, now the federal security secretary.