A man who holed up in a post office in a suburb northwest of Paris with two hostages on Friday surrendered and has been arrested, a police source said.
"There was no assault, the man gave himself up", the source said, adding that the hostages were "shocked but not injured".
The man equipped with a military weapon had taken an unconfirmed number of hostages at the post office in the town of Colombes, not far outside the capital, French media reported earlier.
"I cannot confirm or deny whether it is linked to terrorism," an official at the city prosecutor's office told Reuters earlier, declining to give further details.
The area around the building in Colombes, a city northwest of Paris, had been cordoned off, with a helicopter flying overhead and elite security forces on the ground.
The incident came on a day when French and German authorities arrested more than a dozen people with suspected links to the Islamic State group and a Paris train station was evacuated, with Europe on alert for new potential terrorist attacks.
The arrests followed several raids across Belgium on Thursday during which police killed two gunmen in a vast sweep against an Islamist network suspected of planning imminent strikes.
Visiting a scarred Paris on Friday, US secretary of state John Kerry met French President Francois Hollande and went to the sites of the city’s worst terrorist bloodshed in decades.
Twenty people, including the three gunmen, were killed last week in attacks on a kosher supermarket and the offices of satirical newspaper Charlie Hebdo as well as police.
Hollande thanked Kerry for offering France support, saying, “You’ve been victims yourself of an exceptional terrorist attack on Sept 11. You know what it means for a country. ... We must find together appropriate responses.”
Underscoring heightened fears, police evacuated the Gare de l'Est train station after a bomb threat as Kerry’s motorcade sped from site to site.
The Paris prosecutor’s office, meanwhile, said at least 10 people were arrested in anti-terrorism raids in the region, targeting people linked to one of the French gunmen, Amedy Coulibaly, who claimed ties to the Islamic State group.
Across Europe, anxiety has grown as the hunt continues for potential accomplices of the three Paris terrorists, and as authorities try to prevent attacks by the thousands of European extremists who have joined Islamic State militants in Syria and Iraq.
“The fight against terrorism must be international,” French foreign minister Laurent Fabius said. “Everybody must act: France, Europe and every country.”
Ripples were visible in faraway Pakistan where about 200 protesters clashed with police outside the French consulate in Karachi after a demonstration against Charlie Hebdo turned violent with at least three people suffering injuries.
After the clashes, the protesters, mainly students from a local university, retreated to a nearby area but refused to leave, as police blocked access to the consulate.
The rallies came a day after Prime Minister Nawaz Sharif led parliament in condemning the cartoons, regarded by many Muslims as offensive.