A man armed with a hammer shouted "this is for Syria" and wounded a policeman before being shot and wounded by other officers outside Notre Dame Cathedral in Paris, one of France's most famous tourist sites.
The Paris prosecutor's office swiftly launched a counter-terrorism investigation into Tuesday's attack, the first since President Emmanuel Macron won power last month and days before the first round of a parliamentary election in France.
Interior Minister Gerard Collomb said the attacker was carrying the identification card of an Algerian student and preliminary information indicated he acted alone.
Dozens of armed police sealed off the area and put the Gothic cathedral into lockdown with nearly 1000 people inside.
The incident came three days after militants drove a van at high speed into pedestrians in London before stabbing revellers on the street and in nearby bars, killing seven people and wounding dozens. That followed a suicide bombing in the northern English city of Manchester that killed 22 people.
Tuesday's attack will put a renewed focus on France and Europe's struggle to deal with unsophisticated, low-tech attacks in the countdown to the first round of the parliamentary election on Sunday.
Macron's rivals portrayed him as weak on security during the presidential election campaign. Collomb said fighting terrorism was the president's "number one" priority.
Anna Levy, an American tourist, said she had been about to enter the cathedral when she heard gunshots.
"It was just scary because you didn't know what was happening. People were just running," she said.
One of those inside the catherdral, Dean Blair, tweeted: "Not the holiday experience wanted. Trapped in Notre Dame Cathedral after police shoot a man. We are with our 2 terrified children."
Macron wants to extend a state of emergency that has been in place since gunmen and suicide bombers killed 130 people in coordinated attacks on entertainment venues in Paris in late 2015.
In total, more than 230 people have died in attacks across France in the past two-and-a-half years, most of them claimed by Islamic State.
