Police cordoned off the area including the former Charlie Hebdo offices after a suspect package was noticed nearby, according the police official.
A Paris police official said that while authorities initially thought two attackers were involved, they now believe it was only one person, who was detained near the Bastille plaza in eastern Paris.
Descriptions of the suspects have not been issued and the motivation for the attack has yet to be determined, but the Charlie Hebdo offices were the site of a radical Islamic terrorist massacre in 2015, perpetrated as punishment for the satirical magazine's publication of satirical cartoons depicting the Prophet Mohammed. An earlier toll had said four were wounded, two seriously.
Initial reports had indicated there were two attackers but police later emphasised there appeared to have been just one. "We know that our two colleagues are injured, but we do not know more for the moment", the source said.
French prosecutors said they are investigating the attack as a possible case of terrorism.
AP reporters saw officers flooding into the neighbourhood, near the Richard Lenoir subway station. Police could not explain the discrepancies.
French police officers patrol after people were wounded in a knife attack near the former offices of satirical newspaper Charlie Hebdo, Friday Sept. 25, 2020 in Paris.
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.
Fourteen people went on trial in Paris on Septemer 2, accused of being accomplices in the attack on the Charlie Hebdo offices in January 2015 that killed 12 people. The threats coincide with the trial of 14 suspected accomplices of the perpetrators of the massacres at Charlie Hebdo and a Jewish supermarket that left a total of 17 dead.
But after several high-profile attacks in recent years, DW's Paris correspondent Lisa Louis said France was still on edge.
French Prime Minister Jean Castex confirmed that four people were injured and cut short a visit he was making in Seine-Saint-Denis, north of Paris.
Manuel Valls, former Prime Minister under Francois Hollande, tweeted: "My emotion following the stabbing attack near the former premises of Charlie Hebdo".