MEXICO CITY — A Venezuelan migrant died while trying to cross the frigid waters of the Rio Grande to reach the United States, Mexico’s National Immigration Institute said Wednesday.

The institute said the river’s water temperature was below freezing; it was unclear if the woman died of drowning, the effects of hypothermia or both.

The institute said Wednesday that a total of four migrants tried to cross the river near Piedras Negras, Coahuila, across the border from Eagle Pass, Texas.

Two of the migrants made it across and were apprehended by the U.S. Border Patrol. Two woman were unable to cross, but one made it back to the Mexican side, where she was treated for signs of hypothermia.