A German tourist was killed and several other people injured in central Paris late Saturday after a man attacked them with a knife and a hammer, the French authorities said. The case stirred fears of renewed Islamist terror attacks in a nation already on edge.

A suspect was arrested nearby shortly after the assault. The authorities said he had serious psychiatric disorders and had told the police he was upset over the death of Muslims in the world, including in Gaza. France’s national antiterrorism prosecutor’s office said it had opened an investigation.

Gérald Darmanin, France’s interior minister, said the suspect first attacked two German tourists shortly after 9 p.m. on the Quai de Grenelle, not far from the Eiffel Tower, killing one of them, a Filipino-born German man, with a knife. The other person, a woman, was not injured, Mr. Darmanin said.

“This person was clearly ready to kill other people,” Mr. Darmanin told reporters in Paris.

France was struck by large-scale Islamist terror attacks in 2015 and 2016, and then by a string of smaller but deadly shootings and stabbings in subsequent years. The country is still on its highest terrorism threat alert after the killing last month of a teacher in northern France.

“We won’t give in to terrorism,” Prime Minister Élisabeth Borne said on X after Saturday’s attack.

Mr. Darmanin did not identify the suspect, but said he was French, was born in 1997 in Neuilly-sur-Seine, an upscale suburb of Paris, and had been on the radar of French intelligence services.

The man was convicted in 2016 for a thwarted effort to carry out a “violent action” and was released in 2020, Mr. Darmanin said, but he did not provide further details.

The suspect, who lives with his parents just south of Paris, has “very serious psychiatric disorders” and is undergoing psychiatric and neurological treatment, Mr. Darmanin said.

A taxi driver who tried to stop the assailant after the German couple were attacked heard the suspect shout, “God is great” in Arabic, Mr. Darmanin said.

After that attack, the assailant fled across the Seine River on the Bir-Hakeim Bridge, which connects the Seventh and the 16th Arrondissements of Paris, Mr. Darmanin said.

He said that a police patrol car called to the scene started pursuing the assailant, who went on to attack two other people — another tourist and a Frenchman in his 60s — with a hammer, injuring one of them in the eye. Their injuries were not life-threatening, Mr. Darmanin added.

The officers arrested the man on a nearby square, where he threatened them “very violently” and tried to attack an officer, who subdued the assailant with a stun gun, Mr. Darmanin said.

During his arrest, the suspect again said, “God is Great” in Arabic, Mr. Darmanin said; added that he was upset by the death of Muslims in Afghanistan and Gaza; and accused France of being “complicit” in Israel’s actions there.

“My condolences go out to the family and loved ones of the German citizen who died this evening in the terrorist attack in Paris, and my thoughts are with the people currently injured and in care,” President Emmanuel Macron said on X.

The assault on Saturday came less than a year before the 2024 Summer Olympic Games in Paris, which will include an opening ceremony on the Seine River that has fueled growing security concerns.