Violence across Mexico after the killing of a cartel boss is hitting trucks, ports and air freight for a critical trading partner to the U.S.

"The country is still very unstable," Mike Vigil, the former Chief of International Operations for the DEA, tells PEOPLE. "The situation can flare up within minutes.”

U.S. citizens and government staff in affected parts of Mexico are being asked to stay at home, work remotely and avoid crowds.

President Claudia Sheinbaum was set to speak at a news conference on Monday morning, the day after the killing of Mexico’s most wanted cartel boss by Mexican authorities incited violence across the country.

Culiacán in northern Mexico has seen a surge in violence as rival factions of the Sinaloa cartel battle for control.

Chaos erupted after the killing of cartel boss Nemesio Rubén Oseguera Cervantes, leaving some usure about their travel plans.

Steelers CB Joe Haden let fans know he was safe but “spooked” in Mexico amid cartel violence after the death of Nemesio Oseguera Cervantes.

"El Mencho," the powerful drug lord the Mexican army killed in a daring raid Sunday, had created what security experts say was one of the most advanced security operations devised to protect a cartel boss.