U.S. missionary in Mexico fatally shot

An American missionary was killed in Mexico on Wednesday, police said.

Preliminary research indicates that Nancy Davis, 59, and her husband were on a road near the Mexican town of San Fernando, Mexico, where they clashed with gunmen in a black pick-up Police Service Pharr, Texas, said in a statement. San Fernando is located south of the border city of Reynosa in Tamaulipas.

"The gunmen tried to stop the victims and accelerated efforts to get away from them," said the police statement. "At a time when armed men fired a gun in the victim's vehicle and a bullet struck the victim Nancy Shuman Davis in the head."

Davis' husband, identified as Sam Davis by friends of the family, drove his truck to "high speed" Pharr International Bridge, which crosses the Rio Grande. Nancy Davis was taken to hospital in nearby McAllen, where he was pronounced dead 90 minutes later.

Texas Public Safety, Immigration and Customs Enforcement, the FBI and U.S. Customs and Border Protection will also help, police said.

The Ministry of the Interior of Mexico said that it was also examining "the purpose of clarifying the facts and take action to punish the person or persons responsible."

Merton Rundell, a professor of missions at Indiana Bible College Union and the Academy and a family friend, told CNN that the couple had lived in Mexico since 1970 and has worked with the evangelical mission to Mexico Proclaimers.

Mary Anne Wheeler, another friend who worked with Davis in the 1990s, said the death of Nancy Davis was a great loss.

"It breathes Mexico," said Wheeler. "It's his love.

"For 40 years she has traveled from Mexico to try to be there as a nurse, a friend, as a spiritual guide and loved them. They lost the best, "she said. "They had a little lady who had a bulldog tenacity and was there for you."

Wheeler said the couple had been shot at before and knew of the dangers of the border.