An attacker armed with a sawn-off shotgun on Saturday wounded a Greek Orthodox priest in a shooting in the French city of Lyon, a police source said.
Nikolaos Kakavelaki, 52, was closing his church mid-afternoon when he was attacked and is now in a serious condition in hospital, said the source, who asked not to be named.
The attacker fled the scene but later Lyon's public prosecutor Nicolas Jacquet announced that a suspect had been arrested.
"A person who could correspond to the description given by the initial witnesses has been placed in policy custody," said Jacquet, adding that the suspect had not been carrying a weapon when he was arrested.
The motive for the attack wasn't clear but it comes at a time when France is already on edge over the killing of three people inside a church and the beheading of a teacher who showed a class a cartoon of the prophet Mohammed.
The priest was shot twice in the chest at point-blank range, according to sources close to the enquiry.
Witnesses heard the gunshots then "saw an individual fleeing and discovered a man with gunshot wounds at the back door of the church," the Lyon prosecutor's office said in a statement.
The interior ministry said that "security and emergency personnel are at the scene," warning people to "avoid the area" where the attack took place. The search for the assailant was underway.
- 'Europe won't bow to terrorism' -
Reacting to Saturday's attack, EU Parliament President David Sassoli said that "Europe will never bow to violence and terrorism".
The Assembly of Orthodox Bishops in France (AEOF) said it "condemned such acts of violence that threaten lives and spread a general climate of insecurity".
The small Orthodox church is situated in a residential area of Lyon which was especially quiet due to the new lockdown measures introduced in France on Friday to stem the growing coronavirus pandemic.
In Paris, Interior Minister Gerald Darmanin opened a crisis cell meeting to consider the situation.
Prime Minister Jean Castex spoke of "the government's determination to allow each and everyone to practice their worship in complete safety and in complete freedom."
The shooting comes just days after three people were killed in a knife rampage inside a church in the southern town of Nice.
A Tunisian suspect was shot by police near the scene of that attack.
France was already tense after the republication in early September of cartoons of the prophet Mohammed by the satirical Charlie Hebdo magazine, which was followed by an attack outside its former offices, the beheading of the teacher and the attack in Nice.
Foreign Minister Jean-Yves Le Drian has warned that French citizens face a security risk "wherever they are", saying alerts had been sent to all French nationals abroad.
France went into a second coronavirus lockdown on Friday but the government has exempted places of worship until Monday, allowing them to celebrate the Christian All Saints' Day on Sunday.
- France on high alert -
France has been on high alert since the January 2015 massacre at Charlie Hebdo marked the beginning of a wave of jihadist attacks that have killed more than 250 people.
Tensions have heightened since last month, when the trial opened for 14 suspected accomplices in that attack.
After the deadly attack in Nice, President Emmanuel Macron announced increased surveillance of churches by France's on-the-street military force, which is to be bolstered to 7,000 troops from 3,000.
Security at schools will also be boosted, he said. Schools are remaining open during the new lockdown.