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.”