Classes were canceled, and a shelter-in-place warning was issued by the U.S. Consulate in Nuevo Laredo, Texas, on Monday morning after gunfire erupted near the city's border with Mexico.

President Andres Manuel Lopez Obrador claimed, without providing details, that the shootings occurred in retaliation for the capture of a cartel boss. Zetas's previous branch, the Northeast cartel, has long ruled the city.

U.S. Consulate in Nuevo Laredo also canceled all visa appointments that day, said the Associated Press News.

"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.

A military officer who was not authorized to speak on the record claimed that the suspect was the leader of the Northeast cartel's infamous "Troops of Hell" killing team.

That group is the cartel's enforcers, and they have had run-ins with the military and police on multiple occasions.

The police identified the detainee as Heriberto Rodriguez Hernandez, aka "Negro 35" or "Negrolo."

Although the name Negro means "Black" in Spanish, it is unclear if this refers to his race.

READ NEXT: Mexico: 5 Decapitated Heads Found Inside Ice Coolers in Tamaulipas as Mexican Drug Cartels Battle for Territory 

The Violence Affects the City Operation

Posting to Facebook just after 6 a.m. Central Time, Mayor Carmen Lilia Canturosas reported "a risk situation at different points of the city" because of gunshots that reportedly began at 4 a.m. Central Time.

The sounds of gunfire may be heard in several online videos, according to Mexico News Daily.

The fighting, in which the military is said to have engaged cartel members, did not result in any reports of injuries or fatalities.

While Canturosas first reported that the education department had decided to delay school opening until 9 a.m., he has now claimed that elementary and secondary school classes have been canceled for the safety of children and teachers.

According to a local transportation group, some bus routes resumed operation by midday on Monday after being suspended early in the day.

The U.S. Consulate in Nuevo Laredo, located over the border from Laredo, Texas, tweeted shortly after 6 a.m., stating that an "emergency situation" had developed due to an arrest operation.

In a separate update, the embassy promised to contact affected individuals directly to reschedule Monday meetings. At 9:20 a.m., the message "the situation has begun to normalize" was issued, urging people to "remain to shelter in place and standby for future information."

The mayor of Nuevo Laredo posted some very similar sentiments on Facebook.

After the arrest of a cartel boss, the group may resort to violence and narco-blockades as vengeance, hindering ongoing security operations and possibly even pressuring the government to release recently apprehended criminals.

The Incident Is Not New to Nuevo Laredo

When top leaders of Mexican drug cartels are arrested, the organizations often cause chaos to either block more arrests or transfers of detainees or pressure the government to release the leaders. Lopez Obrador says the suspect has arrived in Mexico City.

Nuevo Laredo has been struck by cartel violence twice this year, both times after the arrest of a capo.

The American consulate in Nuevo Laredo was closed in March after reports of gunfire and car fires forced the temporary closure of border crossings leading into Laredo, per ABC News.

In March, these incidents occurred after the arrest of Juan Gerardo Trevio, another member of "The Troops of Hell" and the nephew of imprisoned Zetas boss Miguel Angel Trevio.

READ MORE: Will Smith Sends Serious Message to Fans Who Don't Want To Watch His New Movie After Chris Rock Slap at Oscars 

This article is owned by Latin Post.

Written by: Bert Hoover

WATCH: Gunfight along U.S.-Mexico border after cartel boss arrested | Rush Hour - From NewsNation