AP reporters witnessed police "flooding" the east Paris neighborhood.
Two suspects were arrested separately shortly after the stabbing in which two people were wounded, although the links between the two suspects weren't immediately clear.
"Four people have been wounded and it seems that two are in serious condition", he said.
The incident took place near the Charlie Hebdo building that was the scene of a terrorist attack in 2015 in which twelve died. The trial for the 2015 Charlie Hebdo attack is now underway.
France's PNAT specialist anti-terror prosecution office said it has opened a probe into charges of "attempted murder related to a terrorist enterprise" as well as "conspiracy with terrorists".
The Paris metro closed lines in the area and school children were initially kept inside in an area around the attack, a city hall official said.
Kim Jong-un sends rare apology for death of South Korean official
Moon was said to have sent a letter to Kim on September 8, to which Kim responded four days later. But North Korea denied burning his body, saying it could not find him after the shooting.
Jean Castex, France's prime minister, said he "immediately" met with the country's Minister for the Interior to "take stock of the situation".
"I talked to a policeman, who told me they were not looking into big plots at the moment, but rather at lone wolves who might attack people in the streets", she said.
Paul Moreira, a journalist from Premiere Ligne media production company told BFM TV, that two of his colleagues had been wounded.
Earlier in September, Charlie Hebdo republished the images to mark the occasion of the trial.
A suspicious package that had been noticed near the attack site turned out to be harmless, police said.
Charlie Hebdo moved its activities out of the area after the 2015 attack.
Staff, who now work at a secret location, received death threats after it hit the stands. Murmurs broke at the terrorism trial of 14 people, including three fugitives, accused of helping the attackers in the January 2015 killings, as the news of Friday's attack filtered through.
The widows of the two Charlie Hebdo shooters are scheduled to testify at the trial Friday afternoon. Police could not explain the discrepancy.