US President Barack Obama has led a chorus of global condemnation of a wave of attacks in Paris that left more than 120 people dead, as nations pledged solidarity with France.
The co-ordinated killings reverberated around the world after shootings by gunmen shouting "Allahu akbar", explosions and a hostage-taking at a popular concert venue in the French capital.
Countries such as the US, Britain, Spain and India, which have experienced their own mass-casualty attacks, were among the first to voice their condemnation.
"It's an attack not just on the people of France. But this is an attack on all of humanity and the universal values we share," Obama said in an address at the White House late on Friday (local time).
"We're going to do whatever it takes to work with the French people and with nations around the world to bring these terrorists to justice and to go after any terrorist networks that go after our people."
In London, where 52 people were killed and hundreds wounded in a series of co-ordinated suicide bombings in 2005, British Prime Minister David Cameron said: "We will do whatever we can to help."
Jose Manuel Garcia Margallo, the foreign minister of Spain, where 191 people were killed in train bombings in 2004, raised the spectre of a jihadist attack.
"All of this confirms that we are facing an unprecedented challenge, a hugely cruel challenge," he told public television TVE.
Indian Prime Minister Narendra Modi, whose country was hit by two major attacks in 2006 and 2008 that saw a total of 355 people killed, said on Twitter the "news from Paris is anguishing & dreadful".
And in Australia, where a lone gunman reportedly shouting Islamist slogans killed a man outside police headquarters in Sydney last month, Foreign Minister Julie Bishop said "this is indeed a black Friday for France and for the world".
Speaking from Berlin, Prime Minister Malcolm Turnbull said Australia stands shoulder to shoulder with the people of France and with all free people in the battle against terrorism.
"In France and Australia, all around the world, we stand shoulder to shoulder with the people of France and with all free peoples in the battle against terrorism," he said.
France's Jewish community was among the targets of the last attacks Paris in January and Israeli Prime Minister Benjamin Netanyahu added his voice to the condemnation.
"Israel stands shoulder to shoulder with French President Francois Hollande and with the people of France in our common battle against terrorism," he said.
President Recep Tayyip Erdogan of Turkey, where twin bombings on a peace rally in Ankara last month killed 102 people, offered his condolences.
"As a country that knows very well the manner and consequences of terrorism, we understand perfectly the suffering that France is experiencing now," he said.
European Union foreign policy chief Federica Mogherini tweeted that she was "in the process of following with pain and dread the events in Paris".
"Europe is with France and the French people," she said.
Angela Merkel, the chancellor of neighbouring Germany, said she was "profoundly shocked by the news and images from Paris", while Dutch Foreign Minister Bert Koenders tweeted: "Shocked and appalled by new attacks in #Paris. Words are not enough."
In Asia, where people woke up to the news from Paris, Philippine President Benigno Aquino's government, which is preparing to host the annual Asia-Pacific Economic Co-operation summit on November 18-19, said the Paris attacks demanded "heightened security from all of us".
Chinese President Xi Jinping spoke of "these tragic times for the French people" as he condemned "in the strongest ways this barbarous act".
In New York, One World Trade Center, the skyscraper built on the site of the September 11 attacks of 2001, was illuminated in blue, white and red in tribute to the French flag.
"We are reminded in this time of tragedy that the bonds of liberte, egalite, fraternite are not just the values French people share, but we share," Obama said in Washington, referencing the French national motto.
"Those go far beyond any act of terrorism or the hateful vision of those who perpetrated the crimes this evening."