Shocking video footage captured the horrifying moment four Americans were loaded into the flatbed of a pickup truck after they were shot at and kidnapped in Mexico.

The victims, whose names have not been released, were attacked by a group of gunmen moments after they had driven into the border city of Matamoros on Friday.

The FBI said the group entered Matamoros through Brownsville, Texas. They had travelled in a white minivan with North Carolina license plates, and were there to buy medicine ended up caught in the crossfire between two armed groups, according to Mexico President Andrés Manuel López Obrador.

U.S. Ambassador to Mexico Ken Salazar said in a statement Monday that an 'innocent' Mexican citizen died in the attack. 

He did not offer any additional details, but said various U.S. justice agencies were working with their Mexican counterparts to recover the missing U.S. citizens. 

The video shows one of the gunmen escorting a woman to the pickup truck and forcing her to sit on the flatbed. Meanwhile, his cohort is dragging a man across the pavement before two other male victims are dumped in the vehicle.