A drone is displayed Wednesday at Paris store Azur Modelisme. Law enforcement officials in the city are concerned about recent unexplained drone fly-bys of high-security sites, including the Eiffel Tower and the U.S. embassy. Eleanor Beardsley/NPR hide caption

itoggle caption Eleanor Beardsley/NPR

French Ambassador to the U.S. Gerard Araud addresses a solidarity gathering at the Adas Israel Congregation in Washington, D.C., on Wednesday. Araud said last week's attack was "in a sense maybe worse than what we were expecting, because it was done in a very professional way." Nicholas Kamm/AFP/Getty Images hide caption

itoggle caption Nicholas Kamm/AFP/Getty Images

A man walks past a makeshift memorial for French Muslim policeman Ahmed Merabet near the site where he was shot dead by gunmen, close to the headquarters of the French satirical weekly Charlie Hebdo. Joel Saget/AFP/Getty Images hide caption

itoggle caption Joel Saget/AFP/Getty Images

World leaders, including, from the left, Israel's Prime Minister Benjamin Netanyahu, Mali's Ibrahim Boubacar Keita, France's Francois Hollande, Germany's Angela Merkel, EU President Donald Tusk and Palestinian President Mahmoud Abbas march in Paris on Sunday to honor the victims of three days of bloodshed. A White House spokesman acknowledged "we should have sent someone with a higher profile." Philippe Wojazer/AP hide caption

itoggle caption Philippe Wojazer/AP

A man holds a pencil in the air during a minute of silence in Paris on Thursday for the cartoonists and other victims of gunmen on the offices of French satirical newspaper Charlie Hebdo. Matthieu Alexandre /AFP/Getty Images hide caption

itoggle caption Matthieu Alexandre /AFP/Getty Images

General Secretary of the Elysee Palace Jean-Pierre Jouyet, head bowed foreground at left, and the Elysee Palace staff observe a minute of silence on Thursday for victims of the shooting at the satirical newspaper Charlie Hebdo, in Paris on Wednesday. Philippe Wojazer/AP hide caption

itoggle caption Philippe Wojazer/AP

A police bulletin sought the public's help in finding two suspects in the deadly attack on a satirical magazine's Paris offices Wednesday. Pictured are brothers Chérif (left) and Said Kouachi. La prefecture de Police hide caption

itoggle caption La prefecture de Police

A police bulletin sought the public's help in finding two suspects in the deadly attack on a satirical magazine's Paris offices Wednesday. Pictured are brothers Cherif (left) and Said Kouachi. La prefecture de Police hide caption

itoggle caption La prefecture de Police

The stage version of the Hollywood classic An American in Paris combines British, French and American artistic traditions and stars Leanne Cope and Robert Fairchild in the roles made famous by Leslie Caron and Gene Kelly. Marie-Noelle Robert /Courtesy of Theatre du Chatelet hide caption

itoggle caption Marie-Noelle Robert /Courtesy of Theatre du Chatelet

The Four Seasons George V hotel is seen in Paris. Armed robbers held up a convoy of Saudi diplomatic vehicles that was bound for a Paris airport from the hotel, with about $335,000 in cash. Iam Langsdon/EPA /LANDOV hide caption

itoggle caption Iam Langsdon/EPA /LANDOV

Police were checking cars throughout Paris on Monday, including near the Arc de Triomphe, as the city tried to cut air pollution by instituting odd-even driving restrictions. Philippe Wojazer /Reuters /Landov hide caption

itoggle caption Philippe Wojazer /Reuters /Landov

Parisians and tourists sit at a cafe along the Seine River. The mayor of Paris recently closed down a major highway along the river to open it up for pedestrians. Christophe Morin /Landov hide caption

itoggle caption Christophe Morin /Landov