One civilian was killed and three police were wounded on Saturday in a shooting at a public meeting in Copenhagen attended by the controversial Swedish artist Lars Vilks.
Danish police confirmed one civilian had been killed in a shooting and said the suspects had fled in a car.
Ritzau news agency said both Vilks and the French ambassador, who was also attending, were both unharmed, but that three police had been wounded. The gathering was billed as a debate entitled "Art, blasphemy and the freedom of expression".
Just over a month ago, 17 people were killed in France in three days of violence that began when two Islamist gunmen burst into the Paris offices of the satirical weekly Charlie Hebdo, opening fire in revenge for its publication of satirical images of the Prophet Mohammad.
Vilks stirred controversy in 2007 with published drawings depicting Mohammad as a dog which sparked threats from Islamist militant groups. Al Qaeda in Iraq offered $150,000 for his assasination and protests broke out across the Middle East and Sweden.
He has received numerous death threats and has lived under constant protection by the Swedish police since 2010. Two years ago, an American woman who called herself Jihad Jane was sentenced to 10 years in prison for plotting to kill him.
French President Francois Hollande said he had been informed of an attack and expressed his solidarity to Danish Prime Minister Helle Thorning-Schmidt.
Ambassador Francois Zimeray was not hit by the gunshots, Hollande said in a statement, adding that several people may have been wounded and that Interior Minister Bernard Cazeneuve would go to Copenhagen as soon as possible.
French Foreign Minister Laurent Fabius condemned what he called a "terrorist attack" in a separate statement.
In an interview with AFP, Ambassador Zimeray said the attackers fired into the Krudttoenden cafe, where the gathering was taking place, from outside the building. "It was the same intention as [the] Charlie Hebdo [attack] except they didn't manage to get in," he said.
"Intuitively I would say there were at least 50 gunshots, and the police here are saying 200."
Danish TV2 channel have reported there being at least 30 bullet holes in the cafe's window.
"Bullets went through the doors and everyone threw themselves to the floor. We managed to flee the room, and now we're staying inside because it's still dangerous," Zimeray said.
"The attackers haven't been caught and they could very well still be in the neighbourhood."
(Additional reporting by Reuters)
