Search underway for four Americans kidnapped in Mexico

Mexican and US authorities said on Monday they were working to locate four Americans who were shot at by gunmen in northern Mexico and then kidnapped shortly after crossing the border.

The four unidentified Americans were in a white minivan with North Carolina license plates when they entered Matamoros, Tamaulipas, on Friday, the US embassy to Mexico said in a statement, seeking the public's help in identifying the alleged kidnappers.

The armed men allegedly fired on the passengers shortly after their vehicle crossed into Mexico and then herded them into another vehicle before fleeing the scene, the embassy said.

A Mexican official told Reuters three men and one woman were kidnapped.

An innocent Mexican died in the incident, US Ambassador to Mexico Ken Salazar said in a statement.

Mexico's president said the Americans had crossed into Mexico to buy medication.

"I believe it will be resolved, I hope so," President Andres Manuel Lopez Obrador said in a regular news conference on Monday, adding that Mexico's public security ministry was working with the FBI to locate the missing US citizens.

The FBI is offering a $50,000 reward for the return of the four and the arrest of those involved.