Five people linked to last week’s kidnappings and killings of a group of Americans near the Brownsville, Texas border have been arrested, a Mexican official announced Friday.

Irving Barrios Mojica, Attorney General of Tamaulipas, said on Twitter that the arrest warrants were for the crimes of aggravated kidnapping and simple intentional homicide. An additional person was arrested in recent days, Barrios Mojica said.

in a separate cheep On Thursday night, Barrios Mojica said that five vehicles, including a Lamborghini stolen on US soil, were found in Matamoros as part of a joint operation by Mexican officials.

The Gulf cartel apologized Thursday after two Americans were killed in broad daylight kidnappings on March 3 in which four Americans crossed the border into Matamoros, Mexico, just south of the Texas border.

The cartel condemned the violence in a letter obtained by The Associated Press and they said they had handed over the members who were involved. A senior law enforcement official told NBC News that US authorities believe the letter is legitimate.

«The Cartel del Golfo Grupo Escorpiones strongly condemns the events of Friday, March 3, in which an innocent working mother unfortunately died and four US citizens were kidnapped, two of whom died,» reads a translation of the letter. «For this reason, we have decided to hand over those directly involved and responsible for the events that at all times acted under their own determination and indiscipline and against the rules in which the CDG has always operated.»

The four Americans were shot and kidnapped after they entered Matamoros to undergo a medical procedure.

Tamaulipas state governor Américo Villarreal said at a press conference that a woman, identified by her family as LaTavia Washington McGee, and a man, Eric Williams, survived the kidnapping.

Both were taken to a clinic for medical treatment and returned to the United States via an international bridge between Matamoros and Brownsville.

A law enforcement source who helped coordinate his arrival confirmed that McGee arrived at Myrtle Beach International Airport in South Carolina on Thursday night. The police helped her get her out of the airport.

The two victims who died have been identified by relatives as Shaeed Woodard and Zindell Brown.

On Thursday, the remains of Woodard and Brown were turned over to US authorities in Brownsville, the AP reported.

Aliyah McCleod, McGee’s cousin, said the group is from South Carolina and was traveling in a rental vehicle with North Carolina plates when it pulled into Matamoros. Williams’ wife described the group as childhood friends.

A fifth person was on the trip from South Carolina. The traveler left just before the group reached the border because the person did not have the necessary documentation to cross into Mexico, a police official said Wednesday.

That fifth person could be seen riding with the group in video taken by Williams.

A law enforcement official with knowledge of the matter said a woman in the group had been seeking a cosmetic medical procedure. The official said the cartel gunmen targeted the group in a case of mistaken identity.

The Department of State issued a «Don’t travel» alert for Tamaulipas, noting that organized crime, including shootings, murders and kidnappings, is common along the border and in Ciudad Victoria.

In its letter, the Gulf cartel said it respects the «life, tranquility, and integrity of the innocent» and apologized to «Matamoros society… the American individuals and families affected.»

“In addition, the CDG asks society to remain calm because we are committed to ensuring that these errors caused by indiscipline are not repeated. The guilty will pay, no matter who they are,” the letter says.

A 24-year-old man from the state of Tamaulipas, identified only as José N, “was found caring for the victims” and was arrested, Villarreal said. It is not clear what charges he faces.

Ken Dilanian and Minyvonne Burke contributed.