A man has died and two others have been injured in an attack on a street in central Paris.
France's Interior Minister Gérald Darmanin said an attacker had targeted tourists around the Quai de Grenelle, which is close to the Eiffel Tower.
He added that a 26-year-old French national known to security services had been arrested.
The suspect approached a tourist couple and fatally stabbed a German national, he said.
The man was then pursued by police and attacked two other people with a hammer before being stopped with a Taser and arrested. The injured were treated by emergency services.
The injured were treated by emergency services.
Darmanin said the alleged attacker had shouted "Allahu Akbar", Arabic for "God is greatest", and later told police he was upset because "so many Muslims are dying in Afghanistan and in Palestine".
He said the suspect was sentenced to four years in prison in 2016 for planning a separate attack and was on the French security services watchlist.
The man was also known to have suffered psychiatric disorders, Darmanin said.
A police operation was initiated around the Bir-Hakeim metro station on Saturday night, and authorities urged people to avoid the area.
The anti-terrorism prosecutor's office said it had taken charge of the investigation.
Writing on X, formerly Twitter, French President Emmanuel Macron sent his thoughts to all those affected by the "terrorist attack" and thanked the emergency services for their response.
"The national anti-terrorism prosecutor's office now seized will be responsible for shedding light on this matter so that justice can be done in the name of the French people," he said.
- This story was first published by BBC