Mexican officials have arrested a suspect in connection with the kidnapping of four U.S. citizens, two of which were killed.

Jose Guadalupe N., 24, was guarding the house where cartel members held captive and tortured the four Americans — Latavia "Tay" McGee, Eric James Williams, Shaeed Woodard and Zindell Brown.

Authorities have not revealed whether Guadalupe, a Mexican national, is part of the Gulf Cartel, the gang accused of the kidnappings, that operates in the region.

The victims were discovered Tuesday in a wooden shack in Ejido Tecolote, a rural area east of the Mexican city of Matamoros, Tamaulipas, according to Tamaulipas state chief prosecutor Irving Barrios. When the Americans were found, Woodward and Brown had been killed.

FOUR AMERICANS KIDNAPPED IN MEXICO: WHAT WE KNOW

Jose Guadalupe N.

Jose Guadalupe N., 24, was guarding the house where cartel members held captive and tortured the four Americans. (Getty)

Survivors McGee and Williams were transported to Brownsville, Texas, with a law enforcement escort over the Veterans International Bridge. They were taken to Valley Regional Medical Center in Brownsville to receive treatment.

Williams had been shot in the left leg, but his injury was not life-threatening, Tamaulipas Gov. Américo Villarreal said.

The fourth victim was not injured.

TWO OF THE FOUR AMERICANS KIDNAPPED IN MEXICO ARE DEAD, TWO ALIVE: REPORT

Victims loaded into ambulance

A Red Cross worker closes the door of an ambulance carrying two Americans found alive after their abduction in Mexico. (AP Photo)

The four Americans from South Carolina had traveled across the southern border for McGee to undergo a tummy tuck operation, according to relatives.

They were crossing from Brownsville into Matamoros on Friday and had just entered Mexico when their vehicle received gunfire. The group had ended up in the crosshairs of a shootout between rival cartel gangs.

4 Americans kidnapped mexico

A member of the Mexican security forces stands next to a white minivan with North Carolina plates and several bullet holes at the crime scene where gunmen kidnapped four U.S. citizens who crossed into Mexico from Texas. (AP Photo)

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Armed men believed to be members of a Mexican drug cartel forced the victims into the back of a white truck at gunpoint, with two of the victims appearing to be injured or dead as their bodies were dragged across the pavement.

Guadalupe is the only person arrested thus far in connection with the kidnapping and murder of the Americans, but investigators are still looking for other assailants. 

The FBI had offered a $50,000 reward for the victims’ return and the arrest of the abductors.