March 6, 2023, 7:15 PM +06 / Updated March 7, 2023, 12:59 AM +06 By Marlene Lenthang and Antonio Planas The FBI is offering a $50,000 reward for the return of four Americans believed to have been kidnapped at gunpoint during an attack in Mexico on Friday that also led to the death of a Mexican citizen, authorities said. A senior U.S. official told NBC News on Monday that the Americans kidnapped did not cross the border for any criminal purpose. The four Americans crossed into Matamoros, Tamaulipas, in a white minivan with North Carolina plates Friday, the FBI said in a statement. Matamoros is just south of Brownsville, Texas. Shortly after crossing into Mexico they were met with gunfire by unidentified shooters, the release said. The gunmen “herded the four U.S. citizens into another vehicle and fled the scene with them,” the FBI said. U.S. Ambassador to Mexico Ken Salazar said Monday in a statement that an “innocent Mexican citizen was tragically killed” during the kidnapping. Mexican President Andrés Manuel López Obrador said the Americans were in the country to buy medicine. “They are people from the United States who crossed the border to buy medicines and there was a confrontation between groups. The matter is looked into. I think it will be resolved,” López Obrador said Monday during a daily press conference. It is not uncommon for Americans to cross the Southern Border for cheaper medication in Mexico. The senior U.S. official did not endorse the comments of Mexico’s president that the Americans entered his country to buy medicine. A spokesperson with the National Security Council said in a statement Monday the kidnappings were “unacceptable.” “Our thoughts are with the families of these individuals and we stand ready to provide all appropriate consular assistance,” the statement said. “U.S. law enforcement is in touch with Mexican law enforcement. The Departments of State and Homeland Security are also coordinating with Mexican authorities. We’ll continue to coordinate with Mexico to bring those responsible to justice.” The case is under investigation by the FBI and Mexican law enforcement, and the FBI is asking the public for information leading to arrests. Officials did not provide any further details on the abduction and did not identify the victims. The reward money is for the safe return of the kidnapped victims as well as the arrest of those involved in the assault and kidnapping attack. Anyone with information is urged to call the FBI’s San Antonio division at (210) 225-6741. The U.S. State Department has a “Do Not Travel” warning for Tamaulipas state due to “crime and kidnapping.” The department said organized crime activity including gun battles, armed robbery and kidnappings are common along the northern border and in Ciudad Victoria. “Criminal groups target public and private passenger buses, as well as private automobiles traveling through Tamaulipas, often taking passengers and demanding ransom payments,” the warning said.