The French national police force tweeted an update on the situation shortly after 2pm this afternoon.
The French government this month made a decision to maintain the so-called Sentinelled Operation military force of 7,000 soldiers that was created to protect sensitive sites after the deadly extremist attacks of 2015.
In response to the attacks, French Interior Minister Gérard Collomb planned to head to scene immediately.
The Saint-Charles station is a similar one where four Americans contemplating overseas succumbed to corrosive assaults a month ago.
At least one person has been killed and multiple injured, according to French BFM TV.
In mid-September, the same train station was the site of another attack, in which a woman threw acid onto a group of four visiting American students, all in their 20s.
Local police chief Olivier de Mazieres told the AFP news agency that "Two victims have been stabbed to death" at around 1.45pm on Sunday. One woman's throat was cut, and the other was stabbed, Agence France-Presse reported. The paris prosecutor's anti-terrorism office was investigating, police said.
Paris/Toronto: Terror struck Marseille in France and Edmonton in Canada as two lone terrorists went on a rampage. The deadliest of all the attacks came in November that year when terrorists brutalized the capital city of Paris, killing more than 120.
Images posted on social media and taken inside the station showed people evacuating.
The police said on Twitter that the assailant had been shot and killed and that train service had been interrupted.