4 US citizens kidnapped in Matamoros, Mexico, after crossing from Brownsville, Texas

Loading Video…

This browser does not support the Video element.

4 American citizens kidnapped by armed gunmen crossing into Mexico

Four Americans were kidnapped at gunpoint shortly after crossing into Mexico from Brownsville, Texas on Friday. It happened in the Northern Mexican Border City of Matamoros.

Gunmen kidnapped four U.S. citizens who crossed into Mexico from Texas last week to buy medicine and got caught in a shootout that killed at least one Mexican citizen, U.S. and Mexican officials said Monday.

The four came under fire Friday shortly after entering the city of Matamoros from Brownsville, the southernmost tip of Texas near the Gulf coast, in a white minivan with North Carolina license plates, the FBI San Antonio Division office said in a statement Sunday.

MORE: Autopsy of US lawyer found dead in Mexico released

"All four Americans were placed in a vehicle and taken from the scene by armed men," the office said. The FBI is offering a $50,000 reward for the victims’ return and the arrest of the culprits.

Mexican President Andrés Manuel López Obrador said Monday that the four were going to buy medicine and ended up in the crossfire between two armed groups, without offering details.

Loading Video…

This browser does not support the Video element.

U.S. State Department issues travel warnings for Mexico

Before you bring out the sunscreen and beach shorts for Spring Break, you should know that the U.S. State Department has issued one of its highest 'do not travel' warnings for 30 of Mexico's 32 states. Officials are warning that some resorts which were considered as being in safe areas are now being controlled by Mexican drug cartels. Security Expert Greg Dupree joins the Isiah Factor Uncensored to talk about the warning and what you should do if you’re out of the country.

A video posted to social media Friday shows armed men, some wearing tan body armor, load four people into the back of a truck in broad daylight. One was alive and sitting up, but the others appeared to be either dead or wounded.

U.S. Ambassador to Mexico Ken Salazar said in a statement Monday that the Americans were kidnapped at gunpoint and 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. Authorities have provided no other details about who the victims were or where they were from.

Loading Video…

This browser does not support the Video element.

Matamoros is home to warring factions of the Gulf drug cartel, as leadership changes led to violent infighting. Amid the violence, thousands of Mexicans have disappeared.

Shootouts there on Friday were so bad that the U.S. Consulate issued an alert about the danger and local authorities warned people to shelter in place. It was not immediately clear how the abductions could have been connected to that violence Friday.

Tamaulipas state police said people had been killed and injured Friday, but not how many. The state police said on social media that neither law enforcement nor the military were involved in "two armed incidents between unidentified civilians."

MORE: New rule would impose 'severe limitations' on asylum-seekers at US southern border

Victims of violence in Matamoros and other large border cities of Tamaulipas often go uncounted, because the cartels have a history taking bodies of their own with them. Local media often avoid reporting on such incidents out of safety concerns, creating an information vacuum.

Photographs from the scene viewed by The Associated Press show a white minivan with the driver’s side window shot out and all of the doors open sitting on the side of the road after apparently colliding with red SUV. Multiple people were lying in the street beside it surrounded by rifle-toting gunmen.

Their positions appeared to correspond with the video posted online that was taken from another angle, which showed them being dragged across the street and loaded into the bed of a white pickup. One person who was sitting up in the street walks under their own power to the pickup. At least one other appeared to lift his head from the pavement before being dragged to the truck.

MORE: Feds reunite nearly 700 migrant kids separated from their families at US-Mexico border

Tamaulipas state’s many border crossings with Texas make it lucrative for the cartels that move drugs, migrants and guns between Mexico and the U.S.

The State Department’s travel warning for Tamaulipas warns U.S. citizens not to travel there. However, being a border city, U.S. citizens who live in Brownsville or elsewhere in Texas frequently cross to visit family, attend medical appointments or shop. It would also be a crossing point for people traveling deeper into Mexico.

Previously, as the headquarters of the powerful Gulf cartel, Matamoros was relatively calm. For years, a night out in Matamoros was also part of the "two-nation vacation" for spring breakers flocking to Texas’ South Padre Island.

But increased cartel violence over the past 10 to 15 years frightened away much of that business. Sometimes U.S. citizens are swept up in the violence.

Three U.S. siblings disappeared near Matamoros in October 2014 and were later found shot to death and burned. They had disappeared two weeks earlier while visiting their father in Mexico. Their parents said they had been abducted by men dressed in police gear identifying themselves as "Hercules," a tactical security unit in the violent border city.