Riot police fire tear gas at demonstrators during a protest against fare hikes for city buses in Sao Paulo, Brazil, January 8, 2016. Brazilian riot police on Friday fired tear gas and stun grenades to disperse a violent protest against a rise in public transport fares in the country's largest city, Sao Paulo. (Photo by Nacho Doce/Reuters)

Water is seen discharged over the traditional farm houses at Shirakawa-go, the UNESCO World Heritage site on November 9, 2014 in Shirakawa, Japan. This annual drill is held to prevent fire. (Photo by Kaz Photography/Getty Images)

A member of Libyan forces allied with the U.N.-backed government fires a weapon on a pickup truck during a battle with Islamic State militants in Giza Bahreya, in Sirte, Libya October 27, 2016. (Photo by Hani Amara/Reuters)

A Ukrainian serviceman fires a 2S7 Pion self-propelled gun during military exercises near the village of Divychky in Kiev region, Ukraine, October 21, 2016. (Photo by Valentyn Ogirenko/Reuters)

Members of the Iraqi Army fire towards Islamic State militant positions at the south of Mosul, Iraq December 10, 2016. (Photo by Alaa Al-Marjani/Reuters)

Rebel fighters from the Ahrar al-Sham Islamic Movement fire a heavy machine gun during what they said was an offensive to take the northwestern city of Idlib March 24, 2015. (Photo by Khalil Ashawi/Reuters)

A Palestinian student jumps through a fire ring during a military-style show at a school in Rafah in the southern Gaza Strip March 28, 2016. (Photo by Ibraheem Abu Mustafa/Reuters)

People dressed as Hungarian Hussars fire a cannon during re-enactment of the battle against Austrian soldiers of the Habsburg dynasty in Tapiobicske, Hungary April 4, 2016. (Photo by Laszlo Balogh/Reuters)