A Mexican drug cartel has reportedly apologized for the fatal kidnapping of four Americans, claiming five of its members went rogue after mistaking the tourists for drug smugglers.

An unnamed law enforcement official in the state of Tamaulipas provided a letter believed to be authored by the Gulf drug cartel to Unbiased Press. In it, the criminal organization promised to hand over five men who kidnapped LaTavia “Tay” McGee, Eric James Williams, Shaeed Woodard and Zindell Brown on March 3.

The Americans were on on their way to a plastic surgeon’s office in Matamoros when they were ambushed by several gunmen. Ms McGee and Mr Williams survived the attack and are back on US soil, but Woodard and Brown were killed when Mexican authorities found them on Tuesday.

The Gulf drug cartel has now said the kidnappers went against the group’s rules of “respecting the lives of innocent people”. The letter apologized to the residents of Matamoros who witnessed the shooting, the families of the American victims and to a Mexican woman who died after she was caught in the crossfire.

A picture of the five suspected suspects face down on the pavement with their hands tied was also shared AP. They were later found by Mexican law enforcement, said another official, who also spoke on condition of anonymity.

(Reynosa Codigo Rojo/Facebook)

“We have decided to hand over those who were directly involved and responsible in the events, who at all times acted under their own decision-making and lack of discipline,” the letter reads, according to AP.

Mexican prosecutors have not confirmed new arrests in the case.

Mr Williams’ cousin told AP that the kidnap survivor has not accepted the apology from the cartel.

“It’s not going to change anything about the suffering that we went through,” Jerry Wallace said, noting that U.S. and Mexican officials must address the rampant violence stemming from cartel operations.

An expanded version of the letter shared by local media also read: “The Scorpion drug cartel of the Gulf state condemns the attack on March 3, in which a working (Mexican) mother was killed and four American citizens were kidnapped. Two of them were also killed.

“ (The five members) went against the Gulf drug cartels’ rules of respecting the lives and integrity of innocent people. We apologize to the residents of Matamoros … and the American families affected.”

“The Golf Cartel is asking the community to remain calm as we are determined to ensure that this type of mistake is not made again and that those responsible are made to pay.”

(Reynosa Codigo Rojo/Facebook)

The Scorpion faction is known to dominate the Matamoros area and reacts with violence when other criminal organizations threaten to operate in the territory.

They were missing American citizens were found in a rural area east of Matamoros called Ejido Longoreño on his way to the local beach known as Playa Bagdad.

McGee was uninjured while Williams suffered gunshot wounds to the legs.

They returned to the United States the same day they were rescued and are being treated at a hospital in Texas.

Autopsies on the bodies of the two slain victims have been completed and the remains are expected to be returned to the United States, according to CNN. Officials familiar with the investigation previously told the network they believe a Mexican cartel mistook the victims for Haitian drug traffickers.

According to official documents reviewed by Reuters, Mexican investigators also conducted deep background checks on the four victims, whichflagged Williams and Woodard’s previous drug convictions.

A suspect, 24-year-old Jose “N”, was also arrested on the day of the rescue while guarding the scene of the kidnapping.