State Department officials have alerted U.S. citizens in Mexico to shelter in place and contact official emergency hotlines for more information as dangerous conditions persist amid regional unrest and ongoing security operations.
The alert comes on the heels of a Mexican military operation that took place Sunday, Feb. 22, during which Mexican authorities confirmed the killing of drug lord Nemesio Oseguera Cervantes.
Cervantes, also known as El Mencho, was the leader of the Jalisco New Generation Cartel.
Cartel-organized violence erupted following the operation in Tapalpa after Cervantes' death, with vehicles set on fire, hundreds of road blockages, and attacks on gas stations and businesses, according to Mexican authorities.
In response to the widespread unrest, the U.S. Embassy put out new guidance for U.S. citizens in specific locations in Mexico, instructing them to shelter in place.
"U.S. government staff in Guadalajara (Jalisco), Puerto Vallarta (Jalisco/Nayarit), Ciudad Guzman (Jalisco), Tijuana (Baja California), Chiapas, and Michoacan are sheltering in place until all blockades are cleared, and we urge U.S. citizens to do the same," the embassy stated.
U.S. citizens in the region were advised to "seek shelter and minimize unnecessary movements," and to "avoid areas around law enforcement activity."
The embassy added that while "incidents were reported" as recently as Sunday, Feb. 22, "the situation has returned to normal" in Quintana Roo State, which includes Cancun, Cozumel, Playa del Carmen, and Tulum, as well as Sinaloa, and Tamaulipas.
The embassy has directed any impacted travelers to check social media pages run by Caminos y Puentes Federales, or CAPUFE, the Mexican agency responsible for operating and maintaining federally owned roads and bridges, for road closure status, and to "monitor local media for updates."
Travelers have been urged to "follow the directions of local authorities and in case of emergency, call 911," and to "keep family and friends advised of your location and well-being via phone, text, and social media."
Additionally, the embassy shared several emergency numbers to assist U.S. citizens in Mexico. Those calling from the U.S. and Canada can dial 1-888-407-4747, and those calling from overseas, including from Mexico, can dial 1-202-501-4444.
Six Mexican states -- Colima, Guerrero, Michoacan, Sinaloa, Tamaulipas, and Zacatecas -- are currently under Level 4 "do not travel" advisories, according to the U.S. State Department.
Seven more states, including Baja California, Chiapas, Chihuahua, Guanajuato, Jalisco, Morelos and Sonora, are all currently Level 3, indicating Americans should "reconsider travel" to those regions.
Mexican states including Aguascalientes, Baja California Sur, Coahuila, Durango, Hidalgo, Mexico City, the State of Mexico, Nayarit, Nuevo Leon, Oaxaca, Puebla, Queretaro, Quintana Roo, Quintana Roo, San Luis Potosi, Tabasco, Tlaxcala, and Veracruz are under Level 2 advisories, indicating travelers should "exercise increased caution" when traveling to those regions.
U.S. officials have not yet released any estimate on the number of American citizens that are unable to leave Mexico safely amid the recent unrest, nor has the department indicated if it is aware of any deaths or injuries to Americans in Mexico.
An official told ABC News the State Department has already been in contact with hundreds of individuals via the emergency phone lines.
Impact on flights, airports in Mexico
Flights were disrupted in Puerto Vallarta and Guadalajara due to availability of flight crews, the embassy said Monday.
The embassy said "all other airports in Mexico are open, and most airports are operating normally."
Some flights operated by major U.S. carriers have since resumed operations in Puerto Vallarta and Guadalajara after initially being suspended due to security-related disruptions.
United Airlines said in a statement Monday afternoon that it had resumed flights at both Puerto Vallarta and Guadalajara airports, but that it was still offering a travel waiver "to support customers with options."
American Airlines and Delta both said operations in and out of Puerto Vallarta were still suspended, however a very limited number of flights in and out of Guadalajara had resumed, with travel waivers available to customers looking to rebook.
The embassy has encouraged U.S. travelers to check with their airline to confirm flight status and schedule.
Impact on roads, car travel in Mexico
"Mexican authorities have curtailed operations on some toll roads, reportedly in Puebla, Guerrero, Tamaulipas, Nayarit, San Luis Potosi, Tijuana, Queretaro, Veracruz, and Mazatlán," the embassy said Monday, citing blockades from the day prior.
ABC News' Shannon Kingston, Ayesha Ali and Anne Laurent contributed to this report.
