Hempstead High School students joined the world Tuesday in marking the one-year anniversary of the abduction and disappearance of hundreds of Nigerian girls.

Using the hashtag "bringbackourgirls," the students tied red ribbons outside their school and rallied in support of the 219 girls kidnapped by Boko Haram.

Some activists also marked the anniversary of the mass abduction from a school in Chibok, a town in northeast Nigeria, with a change in their slogan from "Bring Back Our Girls -- Now and Alive" to "Never to be Forgotten."

Nigerian President-elect Muhammadu Buhari said in a statement that he can't promise to find the schoolgirls abducted by Islamic extremists. He said their whereabouts are unknown, adding "We do not know if the Chibok girls can be rescued."

Pakistani activist Malala Yousafzai, meanwhile, promises the girls scholarships and says they must never lose hope. The 17-year-old Nobel Prize laureate chastises outgoing Nigerian President Goodluck Jonathan and the international community, saying they haven't done enough to rescue the girls.

Boko Haram has kidnapped more people since then.