Multiple attacks in Paris claimed by Islamic State jihadists increased the pressure on some 20 countries and organizations meeting in Vienna on Saturday to overcome deep divisions and help end Syria's civil war.

Witnesses said that the gunmen who killed almost 130 people in Friday's wave of attacks shouted "Allahu akbar" ("God is greatest") and blamed French military action in Syria against Islamic State (IS) extremists.

For residents of the bustling Indian city of Mumbai, the horrific attacks in Paris on Friday night carry somber echoes of a bloody series of killings in their own city seven years ago.

A total of 166 people were killed in November 2008 when Islamist gunmen stormed luxury hotels, the main railway station, a Jewish center and other sites in the booming metropolis, the financial heart of India.

U.S. President Barack Obama led a chorus of global condemnation of a wave of attacks in Paris on Friday that left at least 127 people dead, as nations pledged solidarity with France.

The coordinated killings reverberated around the world after the shootings by gunmen shouting "Allahu akbar", explosions and a hostage-taking at a popular concert venue in the French capital.

"This time it's war," declared the Le Parisien daily, as France's media reacted with horror but determination after Friday's wave of attacks that left at least 120 dead.

Center-right daily Le Figaro took up a similar theme, splashing with the headline "War in central Paris" amid scenes of carnage at several locations in the French capital.

The attacks which left at least 120 dead in Paris on Friday are the deadliest in Europe since the Madrid train bombings in March 2004.

- January 7-9, 2015, France: Two men armed with Kalashnikov rifles storm the Paris offices of Charlie Hebdo, a weekly known for satirical caricatures of Islam and other religions. They kill 12 people including eight cartoonists and journalists as well as two police officers, before fleeing. A policewoman is killed just outside Paris the following day in a shooting investigators later link to the Charlie Hebdo attack. A gunman takes hostages at a Jewish supermarket, four of whom are killed. The Charlie Hebdo attackers and the hostage-taker are killed in separate shootouts with police.

Singapore on Saturday raised its security alert level following a wave of bombings and shootings in Paris that left at least 120 people dead, the interior minister said.

"These attacks show that no country is immune, even when there is a state of heightened security," Home Affairs Minister K. Shanmugam said in a statement.

More than a hundred people were gunned down at the Bataclan theater in Paris late Friday during a concert by the U.S. band Eagles of Death Metal.

The 1,500 capacity venue, which was sold-out, is one of the biggest in Paris but a Friday night out for hundreds of young rock fans was suddenly turned into "a bloodbath," for a full 10 minutes, witness Julien Pearce a reporter for France's Europe 1 radio station, told CNN.

The Belgian authorities said Saturday they have boosted checks on their borders, especially with France, following attacks in Paris that have left at least 120 people dead.

The authorities also urged increased vigilance for big events in Belgium over the weekend but said it was not necessary to increase the alert level.

Sirens blaring, blood on the roads, weeping relatives: nightmare scenes played out on the streets of Paris on Friday night as at least 120 people were killed in simultaneous attacks.

Pierre Montfort lives close to a Cambodian restaurant on Rue Bichat, where one of seven attacks took place in a night of bloodshed not seen in decades.

Hassan Rouhani on Saturday postponed what would have been the first visit to Europe by an Iranian president in 10 years after attacks in Paris that he described as "crimes against humanity."

Rouhani had been due to hold talks in Rome on Saturday with Pope Francis as well as Italian counterpart Sergio Mattarella and Prime Minister Matteo Renzi before traveling on to the French capital.