The attacker was arrested after seriously injuring one person and lightly injuring two others; unclear pattern.
A man launched a knife attack at Gare de Lyon in Paris, injuring three people before being arrested by the police.
Authorities gave no immediate information on a possible motive for the attack, which took place around 8 a.m. (0700 GMT) on Saturday, as the French capital prepares to host the Olympic Games in been in less than six months.
One person was seriously injured in the abdomen, while two others suffered minor injuries in the attack.
Police said the suspect, a Malian national, presented officers with an Italian driving license indicating his date of birth as January 1, 1992.
He was subdued by passers-by before railway police arrived, police said.
“A thank you to those who subdued the man who committed this unbearable act,” Interior Minister Gérald Darmanin said on X.
The Paris prosecutor’s office has opened an investigation into the attack, while the national “anti-terrorism” prosecutor’s office has declared that it is observing the procedure at this stage.
Gare de Lyon is the largest mainline hub in France, with more than 100 million passengers passing through it each year.
Train operator SNCF said the area between concourses one and three was temporarily inaccessible, adding that services to the Paris region had been delayed due to an “act of criminal intent”.
The Olympic Games are due to open on July 26 with a large outdoor ceremony along the Seine, a major security challenge in the city which has been hit several times by attacks, notably in 2015.
Most recently, in December, a man targeted passers-by near the Eiffel Tower, killing a German tourist with a knife and injuring two others.