Fire fighters, emergency service vehicles and a helicopter in Moskovsky Prospekt at the entrance to Tekhnologichesky Institut station of the St Petersburg metro in the aftermath of an explosion which occurred in a train at 14:40 Moscow timeon April 3, 2017. (Photo by Peter Kovalev/TASS)

People spray water in the street ahead of “Songkran”, the annual Thai New Year water-throwing festival, in Kowloon City, Hong Kong, China, 09 April 2017. The pouring of water is a key element in the festival as it represents purification and the washing away of one's sins and bad luck for the year. The event also includes a “Miss Songkran” pageant where contestants are clothed in traditional Thai dress, and a winner is crowned. This year's “Songkran” will begin in Thailand on 13 April 2017. (Photo by Alex Hofford/EPA)

A skier in a costume attempts to cross a pool of water at the foot of a ski slope while competing in the annual “Gornoluzhnik” amateur event marking the end of the ski season, at the Bobrovy Log ski resort in the suburbs of the Siberian city of Krasnoyarsk, Russia, April 16, 2017. (Photo by Ilya Naymushin/Reuters)

A sticker is seen at the Rocky Mountain Guns and Ammo store in Parker, Colorado July 24, 2012. The killing of 12 people at a midnight screening of the new Batman movie in the Denver suburb of Aurora may spark a fresh round of soul-searching on America's relationship with guns but few predict any real change in the law. (Photo by Shannon Stapleton/Reuters)

Paint splattered police officers look on during clashes outside Top Shop on Oxford Street, during marches in protest at government cuts on March 26, 2011 in London, England. Thousands are taking part in the Trades Union Congress (TUC) organised march to Hyde Park where a rally will take place. Police say they are deploying 4500 officers. (Photo by Dan Kitwood/Getty Images)

A protester uses molotov cocktails against riot police during May Day protests on May 1, 2010 in Athens, Greece. (Photo by Milos Bicanski /Getty Images)

“Horst Ludwig Wessel (October 9, 1907 – February 23, 1930) was a German Nazi activist who was made a posthumous hero of the Nazi movement following his violent death in 1930. He was the author of the lyrics to the song “Die Fahne hoch” (“The Flag On High”), usually known as Horst-Wessel-Lied (“The Horst Wessel Song”), which became the Nazi Party anthem and, de facto, Germany's co-national anthem from 1933 to 1945”. – Wikipedia

Photo: German Nazi activist Horst Wessel (left) at the head of a parade of S.A. stormtroopers, or “brownshirts”, in Nuremberg, Germany, 1929. (Photo by Hulton Archive/Getty Images)