Attackers affiliated with DAESH, according to the group's affiliate news agency. Another victim in critical condition after five people were held hostage at a church in Saint-Etienne-du-Rouvray near the northern city of Rouen.
Two attackers killed a priest with a blade and seriously wounded another hostage in a church in the Normandy town of Saint-Etienne-du-Rouvray in northern France Tuesday morning during mass.
The attackers, whom the DAESH later in the day referred to as its soldiers, were shot dead by the French police after which the area was being swept for explosives, according to TRT World.
French media reported the attackers slit the throat of the priest. Interior Ministry spokesperson Brandet confirmed one of the hostages had been killed and said another was in critical condition.
The knifemen launched their assault by taking five people hostage inside the church in Saint-Etienne-du-Rouvray, south of Rouen. A sixth person managed to escape. The hostages included a priest, two nuns and two worshippers according to BFM TV.
French President Francois Hollande said two hostage takers who killed a priest in a church in Normandy, northern France, were terrorists who had pledged allegiance to DAESH.
"DAESH has declared war on us, we must fight this war by all means, while respecting the rule of law, what makes us a democracy," he told reporters at the scene in Saint-Etienne-du-Rouvray, using an Arab acronym for the extremist group.
The DAESH-affiliated Amaq news agency said two of their "soldiers" carried out the Normandy church attack in France. "They carried out the operation in response to the call to target the countries of the crusader coalition," the Amaq statement said.
Prime Minister Manuel Valls branded the attack "barbaric" and said it was a blow to all Catholics and the whole of France.
"We will stand together," Valls said on Twitter.
"Horror. Everything is being done to trigger a war of religions," tweeted Jean-Pierre Raffarin, a former conservative prime minister who now heads the Senate's foreign affairs committee.
The Vatican condemned the "barbarous killing" of the priest, saying Pope Francis was horrified by the news.
"We are particularly shocked because this horrible violence took place in a church, in which God's love is announced," said Vatican spokesperson Father Federico Lombardi.
He said the pope was feeling "the pain and horror of this absurd violence" and "condemned in the most radical way any form of hate".
The incident comes as France remains on high alert nearly two weeks after Tunisian Mohamed Lahouaiej Bouhlel mowed down a crowd of people celebrating Bastille Day in the southern city of Nice, killing 84 and injuring over 300.
The attack was the third major strike on France in 18 months and was claimed by DAESH.