NEW  YORK (CBSNewYork) — The Empire State Building will again join the Eiffel Tower and remain dark Saturday to mourn the 129 people killed, including one American, in terror attacks across Paris Friday.

The United States and countries around the world are showing solidarity with France following the attacks.

The World Tradeicon1 Empire State Building To Remain Dark In Show Of Sympathy For Paris Terror Attack Victims Center spire was lit in the colors of the French flag Friday night.

Web Extra: Attacks Timeline | Photos | Videos | CBSN |Continuing Coverage

Mayor Bill de Blasio also issued a directive for all flags to fly at half-staff  in honor of the victims. City Hall’s clock tower will be lit blue white and red Saturday night, the mayor’s office said.

“Today, New Yorkers are joining together to remember the Parisians whose lives were tragically taken in yesterday’s attacks. Let us each take a moment to honor these victims and the people of Paris who are bravely soldiering on in the face of terrible loss,” de Blasio said in a statement. “New York City is proud to stand with France and share their clear message: these cruel attempts to intimidate and threaten the people of Paris will not succeed.”

Social media is awash with public buildings around the world lit up in the French colors of blue, red, and white. Among those were the Sydney Opera House in Australia and the Christ the Redeemer statue in Brazil.

London’s Tower Bridge will be illuminated in the colors of France’s flag Saturday night.

ISIS admitted responsibility Saturday for orchestrating the deadliest attacks on France since World War II.

French President Francois Hollande vowed to attack the Islamic State group without mercy and said this was an act of war.

During a news conference Saturday afternoon, a French official said at least 129 people died Friday night in shootings at Paris cafes, suicide bombings near France’s national stadium and a hostage-taking inside a concert hall. Another 352 or so were injured, dozens critically.