The FBI has reported that four American citizens who crossed the U.S.-Mexico border from Texas were shot at, threatened with firearms, and may have been abducted in Matamoros.

Special Agent Oliver Rich, who leads the FBI's San Antonio Division, announced on Sunday that the agency is requesting the public's help in finding the individuals who were last spotted in the northern Mexican city of Matamoros, Tamaulipas. The four have been unaccounted for since Friday, March 3rd.

That day, "four Americans crossed into Matamoros, Tamaulipas, Mexico driving a white minivan with North Carolina license plates. Shortly after crossing into Mexico, unidentified gunmen fired upon the passengers in the vehicle. All four Americans were placed in a vehicle and taken from the scene by armed men," the FBI said in a statement.

Matamoros is a city in the northeastern Mexican state of Tamaulipas, situated along the southern bank of the Rio Grande, which forms the border between Mexico and the United States. It is located directly across from the city of Brownsville, Texas.

The search for the missing Americans is being aided by investigators from the FBI and its federal partners, as well as Mexican law enforcement agencies. Matamoros, where the Americans were last seen, is known for having rival factions of the Gulf drug cartel, and the violence in the area on Friday was severe enough for the U.S. Consulate to issue an alert. The city is situated on the U.S.-Mexico border, opposite the Texan city of Brownsville.

On Friday, the same day the Americans went missing, Tamaulipas state police reported that several people had been killed or injured but did not disclose the exact number of victims.

The FBI Offers $50,000 Reward in Matamoros Kidnapping

The FBI is now offering a reward of $50,000 for any information leading to the safe return of the missing Americans, as well as the capture of those responsible for their disappearance. The FBI, along with its federal partners and Mexican law enforcement agencies, is actively investigating the case.

Anyone with information regarding this investigation is encouraged to call FBI San Antonio Division at 210-225-6741. Tips can also be submitted online at https://tips.fbi.gov. These tips can be submitted anonymously.