The FBI is offering a $50,000 reward for the return of four Americans believed to have been kidnapped at gunpoint in Mexico on Friday, with the agency asking the public for information leading to arrests. 

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. 

The case is under investigation by the FBI and Mexican law enforcement. 

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 that 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.