Four U.S. citizens were kidnapped in Mexico just hours after crossing the southern border into Matamoros, the FBI said Sunday night. The kidnapping occurred Friday. The four people drove into Matamoros in a white minivan with North Carolina license plates, the bureau said in a statement. “Shortly after crossing into Mexico, unidentified gunmen fired upon the passengers in the vehicle,” the statement continued. “All four Americans were placed in a vehicle and taken from the scene by armed men.” The FBI is asking for the public’s assistance in identifying the suspects—and is offering a $50,000 reward for information that leads to the victims’ safe return and arrests of the suspects involved.