Snipers ambushed a rafting party on the Rio Grande, firing a hail of bullets from cliffs on the Mexican side of the border and killing a man as he tried to drag his wounded wife to safety, officials said.

The river guide accompanying the couple also was wounded. He and the woman were hospitalized in stable condition.Authorities were seeking up to four snipers.

"There was no provocation or anything. It was just an attack," said Mike Cox, a spokesman for the Texas Department of Public Safety in Austin. "The woman says it was a nightmare."

Cox said it was the second time this year that American tourists have reported being shot at from the bluffs on Mexico's side of the Rio Grande.