On September 1, 2004, Chechen militants stormed an elementary school in the town of Beslan in the Russian republic of North Ossetia. They took 1,100 teachers, children, and their relatives hostage, demanding the withdrawal of federal forces from Chechnya as a condition for their release. On September 3, 2004, Russian security forces stormed the building, resulting in a battle in which more than 330 hostages died, including 186 children. Here: A man assists two young hostages who managed to escape from the school building after special forces entered the school in Beslan, North Ossetia, Friday 03 September 2004. (Photo by Yuri Kochetkov/EPA)

Colorado Gov. John Hickenlooper shows off his socks--one with Democratic presidential candidate Bernie Sanders and the other with Republican candidate Donald Trump – before entering his former brewpub for a book signing event to mark the release of his autobiography Thursday, May 26, 2016, in Denver. Hickenlooper, who is term-limited, is doing book talk rounds this week, reviving speculation that he is positioning himself to join Hillary Clinton's presidential campaign ticket. (Photo by David Zalubowski/AP Photo)

In this September 4, 1963, file photo, a police officer carries off a demonstrator holding a Confederate flag after a group of demonstrators protested enrollment of two African-Americans at Ramsay High School in Birmingham, Ala. The Confederate battle flag has been removed from South Carolina's Statehouse grounds, in the wake of the massacre of nine African-Americans, including a state senator, at an historic black church in Charleston in June 2015. (Photo by AP Photo)

A fellow officer comes to the aid of injured patrolman C.V. Satt, who was pelted with rocks and beer bottles during a clash between police and relief demonstrators in Denver September 23, 1935. (Photo by Henry G. Eisenhand/AP Photo)

A Palestinian protester sets fire to himself as he throws a molotov cocktail during clashes with the members of the Israeli armed forces in the West Bank city of Hebron, 13 October 2015. The past 12 days have seen the worst spell of street violence in Israel and the Palestinian areas in years, stirred in part by Muslim anger over perceived changes to the status quo observed at a disputed Jerusalem holy site. Sixteen Palestinians from the West Bank and Jerusalem have been killed, but more than half of them have been attackers shot dead after or during attempts to stab Israelis. (Photo by Abed Al Hashlamoun/EPA)

A crew members walks on the flight deck past Super Etendard fighter jets aboard France's Charles de Gaulle aircraft carrier on missino in the Gulf, January 29, 2016. (Photo by Philippe Wojazer/Reuters)

This photo released by the Cleveland Animal Protective League shows Lurleen, the nursing mother and Noland the puppy snuggling up Wednesday, June 19, 2013, in Cleveland. Lurleen already is caring for four newborn kittens and now is nursing the orphaned week-old pit bull puppy in Cleveland. (Photo by AP Photo/Cleveland Animal Protective League)

Masked women shout slogans during a demonstration marking the Latin American Day for Decriminalization of Therapeutic Abortion in Managua, Nicaragua, where abortions are illegal, on September 28, 2012. (Photo by Esteban Felix/Associated Press)