Gunfire broke out across the Mexican border city of Nuevo Laredo early Monday, prompting the cancelation of classes and an advisory from the U.S. Consulate to shelter in place.

President Andrés Manuel López Obrador said the shootings came in response to the arrest of a cartel leader, but did not elaborate. The city has long been dominated by the Northeast cartel, an offshoot of the old Zetas gang.

The U.S. Consulate in Nuevo Laredo cancelled visa appointments for the day.

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"There is an emergency situation in Nuevo Laredo following an arrest operation. Reports of gunfire in multiple locations in the city. Shelter in place and standby for further information," the consulate said.

AF! Mexican police in Nuevo Laredo

The AFI, the Mexican law enforcement equivalent of the FBI, was on patrol in Nuevo Laredo, Mexico, on August 1, 2005. Gunfire and Violence in Nuevo Laredo on Nov. 28, 2022, were caused by the arrest of a local cartel leader. Schools in the city were forced to close because of the violence. (Janet Schwartz/MCT/Tribune News Service via Getty Images)

Many cartels in Mexico react to the arrest of leading members by creating chaos, either to avoid the detention or transfer of suspects, or to pressure authorities to release them. López Obrador said the suspect had already been taken to Mexico City.

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Bus services stopped running, Mayor Carmen Lilia Canturosas reported, "due to the situation in the city." She reported "risk situations at different points in the city."

In videos posted on social media, bursts of gunfire could be heard in Nuevo Laredo in the pre-dawn hours.

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By mid-day Monday, the mayor tweeted "the situation in the city is starting to normalize."