A gunman gestures after assassinating Andrey Karlov, the Russian ambassador to Turkey, at a photo exhibition in Ankara, Turkey, on Monday, December 19. Turkish Interior Minister Suleyman Soylu said the gunman was Mevlut Mert Altintas, a Turkish police officer. In a video circulating on social media, the shooter was heard shouting, "Allahu akbar (God is greatest). Do not forget Aleppo! Do not forget Syria! Do not forget Aleppo! Do not forget Syria!" Russia is the most powerful ally of the Syrian regime and has carried out airstrikes to prop up embattled leader Bashar al-Assad. Karlov, 62, had served in Ankara since July 2013. Burhan Ozbilici/AP

Fireworks explode at the San Pablito market in Tultepec, Mexico, on Tuesday, December 20. Authorities say dozens were killed at the market, which was especially busy with people buying fireworks for the holidays. JOSE LUIS TOLENTINO/AFP/Getty Images

Authorities examine a truck that crashed into a crowded Christmas market in Berlin on Monday, December 19. At least 12 people were killed and 48 injured in what police are investigating as a terrorist attack. RAINER JENSEN/EPA

A swimmer jumps into an icy river in Shenyang, China, on Tuesday, December 20. VCG//Getty Images

US President-elect Donald Trump is greeted by the Azalea Trail Maids after arriving for his "thank you" rally in Mobile, Alabama, on Saturday, December 17. Mobile marked a turning point for Trump's campaign in August 2015. Prior to that night, it wasn't clear how much support Trump's campaign would garner. But one glance at the crowd of some 30,000 supporters solidified that there was something significant happening. "This is where it all began," the President-elect told the crowd on Saturday. Evan Vucci/AP

Annie Glenn rests her hand on the casket of her husband, former astronaut and US Sen. John Glenn, as he lies in repose at the Ohio Statehouse on Friday, December 19. Glenn, the first American to orbit the Earth, died December 8 at the age of 95. John Minchillo/AP

Zein, a boy from Idlib, Syria, looks for his family members after crossing into Turkey on Saturday, December 17. Idlib could be the next major war zone in Syria after the battle for Aleppo ends. Idlib is one of the few remaining footholds that rebel groups still have in the country. Emrah Gurel/AP

People watch a cockfight in Santo Domingo, Dominican Republic, on Sunday, December 18. Cockfighting is a legal sport there. ERIKA SANTELICES/AFP/Getty Images

Former football star Aaron Hernandez laughs with defense attorney Jose Baez during a hearing in Boston on Tuesday, December 20. Hernandez has pleaded not guilty to two counts of first-degree murder in the 2012 deaths of Daniel de Abreu and Safiro Furtado. He is already serving a life sentence after being convicted of the 2013 killing of Odin Lloyd. Angela Rowlings/AP

Big-wave surfer Nic Lamb wipes out while competing in Nazare, Portugal, on Tuesday, December 20. FRANCISCO LEONG/AFP/Getty Images

Villagers touch one of the three elephants that were fatally struck by a speeding train in India's Assam state on Saturday, December 17. Anupam Nath/AP

Police inspect a body in Zurich, Switzerland, after a gunman walked into an Islamic center and fatally shot three people on Monday, December 19. The suspect's body was found near the site of the attack, and it was assumed that he committed suicide. ENNIO LEANZA/EPA

Members of the Venezuelan militia shout slogans against the opposition during a pro-government rally in Caracas, Venezuela, on Saturday, December 17. The country is facing deep economic chaos after the currency crashed and inflation skyrocketed. Fernando Llano/AP

An artist performs at the inauguration of an ice-skating rink in Milan, Italy, on Friday, December 16. Luca Bruno/AP

Russian President Vladimir Putin, center, attends a farewell ceremony for Andrey Karlov, the Russian ambassador to Turkey, on Thursday, December 22. Karlov, 62, was assassinated while attending a photo exhibit in Ankara, Turkey. He is survived by a wife and son, according to the Russian Embassy. Alexei Nikolsky/AP

Worshippers gather around a huge incense burner as they pray at a Buddhist temple in Tokyo on Tuesday, December 20. Shizuo Kambayashi/AP

Ahmad Khan Rahimi, the man accused of setting off bombs in New Jersey and New York in September, is led into court Tuesday, December 20, in Elizabeth, New Jersey. Through his attorney, he pleaded not guilty to charges connected with the police shootout that led to his capture. Mel Evans/AP

Tree-climbing goats feed in an argan tree in Essaouira, Morocco, on Saturday, December 17. Creative Touch Imaging Ltd/NurPhoto/ZUMA Press

A protester lies on the ground in Pretoria, Congo, after police fired rubber bullets on those protesting President Joseph Kabila on Tuesday, December 20. JOHN WESSELS/AFP/Getty Images

Mary Barrett and her daughter Rebecca react as Iowa's six electors cast their Electoral College votes for Donald Trump at the Statehouse in Des Moines on Monday, December 19. In all, Trump received 304 electoral votes to Hillary Clinton's 227. Several "faithless electors" voted for other candidates. Charlie Neibergall/AP

Mangled vehicles rest on the shoulder of Interstate 95 after a 55-vehicle crash left at least two people dead in Baltimore on Saturday, December 17. Icy roads caused multiple-car pileups in Virginia, Maryland and Oklahoma, authorities said. Karl Merton Ferron/AP

An Iraqi Special Forces sniper scans for a target in Mosul, Iraq, on Tuesday, December 20. Iraq is trying to retake the city from ISIS. Manu Brabo/AP

People skate on the black ice of the Melchsee in Obwalden, Switzerland, on Wednesday, December 21. The lake is normally covered in snow during winter. URS FLUEELER/EPA

The Rev. Kojo Nantambu, center, was among at least 39 protesters who were arrested at North Carolina's Legislative Building on Friday, December 16. Hundreds were at the building to protest a Republican "power grab," according to The News & Observer in Raleigh. The GOP-controlled General Assembly passed two pieces of legislation that stripped duties from Republican Gov. Pat McCrory so that the power of his successor, Democratic Attorney General Roy Cooper, would be curtailed. (Cooper defeated McCrory in November.) McCrory said in a statement that the laws were "hardly extreme changes" and intended to fix a "broken election process" and "enhance" education policies. Ethan Hyman/AP

People dressed in Santa Claus costumes sit in a Madrid bar after taking part in a Santa run on Saturday, December 17. Paul White/AP

A fisherman catches a fish on an ice-covered lake near Nove Mesto, Czech Republic, on Saturday, December 17. FILIP SINGER/EPA

Alcoholic drinks burn during a ceremony near Kabul, Afghanistan, on Tuesday, December 20. Afghan officials burned 98 tons of opium, heroin, hashish and alcoholic drinks. Massoud Hossaini/AP

A mourner reacts in Ramallah, West Bank, after spreading his face with the blood of Ahmad al-Kharoubi, a 19-year-old Palestinian who was fatally shot during clashes with Israeli soldiers in Jerusalem on Thursday, December 22. A spokeswoman with the Israeli army said soldiers were attacked as they tried to demolish the home of a man who went on a deadly shooting rampage in October, according to Agence France-Presse. ABBAS MOMANI/AFP/Getty Images

A Chinese national, living in Venezuela, looks for his passport in the remains of the building where he maintains a home and business in Ciudad Bolivar on Monday, December 19. Hundreds of police and soldiers were deployed to Ciudad Bolivar, where dozens of businesses were destroyed or damaged after massive looting. Alejandro Cegarra/AP