French President Emmanuel Macron said on Monday evening that the French share the shock and sorrow of the Austrian people following the shootings in Vienna, pledging that "our enemies must know who they are dealing with. We will not give in."

"After France, it is a friendly country that is attacked. This is our Europe. Our enemies must know who they are dealing with. We will not give in," said Macron on Twitter.

Earlier in the evening, shootings hit several locations in central Vienna. Austrian Interior Minister Karl Nehammer said the shootings appeared to be a terrorist attack with multiple perpetrators.

France has been placed on its highest level of terrorism alert since three people were killed by a knife attack at the Notre-Dame basilica in the southern city of Nice. On Oct. 16, a history teacher was beheaded outside a middle school in Paris suburbs.