Officials at the US consulate in the Mexican border town of Matamoros were ordered on Monday to “seek shelter on the spot” as gun violence linked to drug cartels rages around them.
Four Americans were kidnapped in the city in March – and two of them eventually killed – after they were believed to be cartel rivals.
Monday’s lockdown was triggered when four people were present Reportedly killed the same day in a shootout with the Mexican military in the border town across from Brownsville, Texas on the Rio Grande.
“We encourage you to take shelter where you are and stay tuned to local news for updates in your area,” it said.
The gunmen attacked a Mexican naval patrol and authorities later seized weapons and tactical equipment, according to a state official.
The Gulf Cartel, a crime syndicate and drug trafficking group, is based in the Mexican border town.
The Jalisco Cartel New Generation is also active in Matamoros.
One of the Americans killed in March, Shaeed Woodard, had traveled to Mexico so his cousin Latavia McGee could have a tummy tuck. The other murdered US citizen, Zindell Brown, belonged to the same group.
The four kidnapping victims had apparently gotten lost in the area on their way to McGee’s medical treatment.
The shocking kidnappings and killings sparked an outcry in Washington, and some lawmakers, such as Senator Lindsey Graham (RS.C.), called for the cartels to be renamed foreign domestic terrorist organizations.
The Gulf cartel acknowledged that some of its members were involved in the crime and apologized in a letter to Mexican police. The group also identified five members they believed to be responsible for the March 3 murders.