Four US citizens kidnapped in Mexico, sparking manhunt

Mexican and US authorities said Monday they were working to urgently secure the safe return of four US citizens shot at and kidnapped by gunmen after crossing the border into Mexico.

The US Federal Bureau of Investigation (FBI) offered a $50,000 reward for help finding the unidentified victims and arresting the perpetrators of the incident, in which a Mexican national was killed.

The US citizens crossed into Matamoros, in Tamaulipas state, on Friday in a white minivan with North Carolina license plates, the FBI said in a statement released by the US embassy in Mexico.

"Shortly after crossing into Mexico, unidentified gunmen fired upon the passengers in the (minivan). All four Americans were placed in a vehicle and taken from the scene by armed men," the FBI said.

Mexican President Andres Manuel Lopez Obrador said that the victims were believed to have entered the country to buy medicines and got caught up in a confrontation between criminal groups.

The Mexican security ministry was working with the FBI to find them, he told reporters.

The US ambassador to Mexico, Ken Salzar, said in a statement that an "innocent Mexican citizen was tragically killed" in the incident.

"US law enforcement officials from numerous agencies are working with Mexican authorities at all levels of government to secure the safe return of our compatriots," he added.

Matamoros, located across the US border from Brownsville, Texas, has been beset by violence linked to drug trafficking and other organised crime.

Tamaulipas's highways are considered among the most dangerous in Mexico due to the threat of kidnapping and extortion by criminal gangs.

The US consulate in Matamoros had issued an alert on Friday warning of police activity in connection with a shooting in the city.