A priest has been killed in an attack by two armed men at his church near Rouen in northern France, police and French media have said.
The armed men entered the church in Saint-Etienne-du-Rouvray during Mass, taking the priest, Fr Jacques Hamel, 84, and four other people hostage.
French TV said shots had been heard after police arrived at the scene. Both hostage-takers are now dead.
Pope Francis decried the “pain and horror of this absurd violence”.
French interior ministry spokesman, Pierre-Henri Brandet, said one of the hostages had been critically wounded.
He said the hostage-takers had been “neutralised” after coming out of the church. Police were now searching the church for explosives.
The area has been cordoned off and police have told people to stay away.
Mr Brandet said the motive of the attackers was not immediately clear, but the investigation into the incident would be led by anti-terrorism prosecutors.
French Prime Minister Manuel Valls has expressed his horror at the “barbaric attack”.
“The whole of France and all Catholics are wounded. We will stand together,” he wrote on Twitter.
President Francois Hollande has arrived in Saint-Etienne-du-Rouvray to be briefed by police.
The Archbishop of Rouen, Dominique Lebrun, who was attending a Catholic gathering in Poland, said: “I cry out to God with all men of goodwill. I would invite non-believers to join in the cry.
“The Catholic Church cannot take weapons other than those of prayer and brotherhood among men.”
A woman who works at a local beauty parlour, Eulalie Garcia, said she had known the priest since her childhood.
“My family has lived here for 35 years and we have always known him,” she said.
“He was someone who was treasured by the community. He was very discreet and didn’t like to draw attention to himself.”
There was no immediate word on the identity of the hostage-takers, but France has been on high alert since the Bastille Day attack in Nice earlier this month, when a man ploughed a lorry into celebrating crowds, killing more than 80 people.
The Nice attack was carried out by Tunisian Mohamed Lahouaiej-Bouhlel, who was not a known jihadist but so-called Islamic State said he had acted in response to its calls to target civilians in countries that have been attacking it.
The BBC’s Lucy Williamson in Paris says the French government has been under huge pressure to prevent further attacks.