World leaders on Tuesday condemned a terror attack in the Austrian capital Vienna that left at least four people dead.

A manhunt is underway for an unknown number of suspects after gunmen went on the rampage through the city center, opening fire on bars, restaurants, and a synagogue. Police shot one attacker dead.

German Chancellor Angela Merkel offered her condolences and voiced solidarity with Austria.

"Islamist terrorism is our common enemy. The fight against these murderers and their instigators is our common fight," Merkel said in a statement tweeted by her spokesman.

Germany's Foreign Ministry called the attacks in neighboring Austria "horrifying and disturbing," saying that Germany "would not give in to hate that is supposed to divide our societies."

Russian President Vladimir Putin also condemned the killings, saying Moscow was ready to boost counter-terrorism cooperation with Austria.

In a telegram sent to Austrian Chancellor Sebastian Kurz, Putin called the attack a "cruel and cynical crime," the Kremlin said in a statement.

'We will not give in'

French President Emmanuel Macron, who was one of the first foreign leaders to react on Monday night, said Europe would not bow to terrorists following the shootings.

"We French share the shock and sorrow of the Austrian people following the attack in Vienna," Macron tweeted in both French and German.

"After France, it is a friendly nation that has been attacked. This is our Europe. Our enemies must know who they are dealing with. We will not give in," he said.

British Prime Minister Boris Johnson tweeted that he was "deeply shocked" and that the "UK's thoughts are with the people of Austria — we stand united with you against terror."

Israeli President Reuven Rivlin and Prime Minister Benjamin Netanyahu responded by saying that Israel stands with Austria in the fight against terrorism.

“Our thoughts and prayers are with the people of Austria as we follow last night’s despicable terrorist attack in Vienna with concern,” Rivlin tweeted.

Netanyahu said that “Israel condemns the brutal attack in Vienna and stands in total solidarity with Austria. Civilized peoples everywhere must unite to defeat the savagery of resurgent Islamist terrorism.”

Trump and Biden decry attack

On the eve of the US election, President Donald Trump tweeted support for Austria following the deadly shootings. 

"Our prayers are with the people of Vienna after yet another vile act of terrorism in Europe. These evil attacks against innocent people must stop," he wrote.

His Democrat rival, former vice president Joe Biden, also condemned the "horrific attack," adding: "We must all stand united against hate and violence."

Indian Prime Minister Narendra Modi said his govenrment stands with the European country.

"Deeply shocked and saddened by the dastardly terror attacks in Vienna. India stands with Austria during this tragic time. My thoughts are with the victims and their families," PM Modi tweeted.

jf/rs (AFP, Reuters)