Photos: World reacts to Brussels terror attacks

The Eiffel Tower is illuminated with the Belgium national colors black, yellow and red in honor of the victims of the today's attacks at the airport and the metro station in Brussels, in Paris, Tuesday, March 22, 2016. Explosions, at least one likely caused by a suicide bomber, rocked the Brussels airport and its subway system Tuesday, prompting a lockdown of the Belgian capital and heightened security across Europe. (AP Photo/Thibault Camus) — The Eiffel Tower is illuminated with the Belgium national colors black, yellow and red in honor of the victims of the today’s attacks at the airport and the metro station in Brussels, in Paris, Tuesday, March 22, 2016. Explosions, at least one likely caused by a suicide bomber, rocked the Brussels airport and its subway system Tuesday, prompting a lockdown of the Belgian capital and heightened security across Europe. (AP Photo/Thibault Camus)

The Belgian flag is projected on Rome’s historical Trevi Fountain to honor the victims of the deadly attacks at Brussels airport and subway, Tuesday, March 22, 2016. Explosions, at least one likely caused by a suicide bomber, rocked the Brussels airport and its subway system prompting a lockdown of the Belgian capital and heightened security across Europe. (AP Photo/Andrew Medichini)

AP Photo/Andrew Medichini

The Brandenburg Gate is illuminated with the Belgium national flag in reaction to the Brussels attacks, in Berlin, Germany, Tuesday, March 22, 2016. (AP Photo/Markus Schreiber)

AP Photo/Markus Schreiber

The Belgian Embassy in Washington, D.C. (草莓传媒/Matt Ritter)

Flowers left at the base of the flagpole at the Belgian Embassy in Washington, D.C. (草莓传媒/Matt Ritter)

Chairman of the Danish Parliament, Pia Kjaersgaard, with flowers for the victims of the Brussels attacks, at the Belgium Embassy in Copenhagen Tuesday, March 22, 2016. Bombs exploded at the Brussels airport and one of the city's metro stations Tuesday, killing and wounding dozens of people, as a European capital was again locked down amid heightened security threats. The Islamic State group claimed responsibility for the attacks. (Philip Davali/POLFOTO via AP) DENMARK OUT — Chairman of the Danish Parliament, Pia Kjaersgaard, with flowers for the victims of the Brussels attacks, at the Belgium Embassy in Copenhagen Tuesday, March 22, 2016. Bombs exploded at the Brussels airport and one of the city’s metro stations Tuesday, killing and wounding dozens of people, as a European capital was again locked down amid heightened security threats. The Islamic State group claimed responsibility for the attacks. DENMARK OUT (Philip Davali/POLFOTO via AP)

After attacks in Brussels, a candle wrapped in a ribbon in the colors of the Belgium national flag and flowers are placed on a table inside the Belgium Embassy in Berlin, Germany, Tuesday, March 22, 2016. (AP Photo/Markus Schreiber)

The Belgian Embassy in central London, with the country's national flag and the flag of the European Union at half staff following the attacks in Brussels, Tuesday, March, 22, 2016. Authorities in Europe and beyond have tightened security at airports, on subways, at the borders and on city streets after deadly attacks Tuesday on the Brussels airport and its subway system. (AP Photo/Alastair Grant) — The Belgian Embassy in central London, with the country’s national flag and the flag of the European Union at half staff following the attacks in Brussels, Tuesday, March, 22, 2016. Authorities in Europe and beyond have tightened security at airports, on subways, at the borders and on city streets after deadly attacks Tuesday on the Brussels airport and its subway system. (AP Photo/Alastair Grant)

The European and the Belgian national flag set on half staff after terrorist attacks in Brussels in front of the Belgium Embassy in Berlin, Germany, Tuesday, March 22, 2016. (AP Photo/Markus Schreiber)

Flowers, a candle and a letter with the words "The culture of freedom will survival your hate" placed after terrorist attacks in Brussels in front of the Belgium Embassy in Berlin, Germany, Tuesday, March 22, 2016. (AP Photo/Markus Schreiber) — Flowers, a candle and a letter with the words “The culture of freedom will survival your hate” placed after terrorist attacks in Brussels in front of the Belgium Embassy in Berlin, Germany, Tuesday, March 22, 2016. (AP Photo/Markus Schreiber)

A woman lays flowers in front of the Belgium Embassy in Berlin, Germany, Tuesday, March 22, 2016, after Tuesday's terrorist attacks in Brussels. (AP Photo/Markus Schreiber) — A woman lays flowers in front of the Belgium Embassy in Berlin, Germany, Tuesday, March 22, 2016, after Tuesday’s terrorist attacks in Brussels. (AP Photo/Markus Schreiber)

Flowers, a candle and a letter with the words 'Defy Terror' - ' Preserve Freedom' are placed in front of the Belgian Embassy in Berlin, Germany, Tuesday, March 22, 2016 after the attacks in Brussels . Deadly attacks Tuesday at the Brussels airport and a metro station in the city are the latest in a string of attacks in Europe in recent years. (AP Photo/Markus Schreiber) — Flowers, a candle and a letter with the words ‘Defy Terror’ – ‘ Preserve Freedom’ are placed in front of the Belgian Embassy in Berlin, Germany, Tuesday, March 22, 2016 after the attacks in Brussels . Deadly attacks Tuesday at the Brussels airport and a metro station in the city are the latest in a string of attacks in Europe in recent years. (AP Photo/Markus Schreiber)

L'hommage de Plantu
— Le Monde (@lemondefr)

(AP Photo/Markus Schreiber)

Police officers perform security checks at Fiumicino airport, near Rome, Tuesday, March 22, 2016. The Italian Interior Ministry announced heightened security measures at major Italian airports following explosions at the Brussels airport and the subway system earlier Tuesday. ITALY OUT (Telenews/ANSA via AP)

Telenews/ANSA via AP

French soldiers patrol in Gare De Lyon railway station in Paris, France, Tuesday, March 22, 2016. Authorities are tightening security at airports and on the streets of European cities after attacks on the Brussels airport and subways system that killed at least one person and injured many others. (AP Photo/Francois Mori)

AP Photo/Francois Mori

An Israeli airport security guard patrols with a dog in Ben Gurion airport near Tel Aviv, Israel, Tuesday, March 22, 2016. After the Brussels attacks, Israel briefly announced that all Israeli flights from Europe were canceled, then reinstated the flights, Israel Airports Authority spokesman Ofer Leffler said. Pini Schiff, former director of security at Ben-Gurion Airport, said the attack in the Brussels airport was 鈥渁 colossal failure鈥� of Belgian security, and he said 鈥渢he chances are very low鈥� that such a bombing could take place in Israel鈥檚 airport. Israel’s Ben-Gurion Airport is considered among the most secure in the world, an outcome stemming from several Palestinian attacks on Israeli planes and travelers in the 1970s. (AP Photo/Ariel Schalit)

AP Photo/Ariel Schalit

A member of the Counter Terrorism Centre (TEK) patrols the area in front of the Parliament in downtown Budapest, Hungary, Tuesday, March 22, 2016. Hungary raised its terrorism awareness level to grade 2 after a series of attacks in Brussels. (Zoltan Balogh/MTI via AP)

Zoltan Balogh/MTI via AP

President Barack Obama pauses as he speaks about the events in Brussels attack before addressing Cubans at El Gran Teatro de Havana, Tuesday, March 22, 2016, in Havana, Cuba. (AP Photo/Pablo Martinez Monsivais)

AP Photo/Pablo Martinez Monsivais

German Chancellor Angela Merkel arrives for a statement on the attacks in Brussels at the chancellery in Berlin, Germany, Tuesday, March 22, 2016. (AP Photo/Markus Schreiber)

France’s President Francois Hollande, center, addresses the medias while Belgium Ambassador to France Vincent Mertens de Wilmars, left, and French foreign minister Jean-Marc Ayrault look on, outside the Belgian embassy, in Paris, Tuesday, March 22, 2016. Bombs exploded at the Brussels airport and one of the city’s metro stations Tuesday, killing and wounding dozens of people, as a European capital was again locked down amid heightened security threats. (AP Photo/Thibault Camus)

AP Photo/Thibault Camus