Six people were lightly wounded on Wednesday by a man wielding a knife at the busy Gare du Nord train station in Paris, police and prosecutors said.

The man was arrested by police at the station – a busy commuter hub which also serves as a departure point for trains to northern France, London and northern Europe – after they opened fire and wounded him, said a police source, who asked not to be named.

Police were treating the stabbings as a criminal act, not a terrorist attack, a source close to the case said.

The attacker sustained a life-threatening chest injury as police fired several rounds, the source said.

An off-duty police officer was the first to act against the attacker, Le Parisien daily said.

"An individual injured several people this morning at the Gare du Nord," Interior Minister Gerald Darmanin wrote on Twitter.

"He was quickly neutralised. Thank you to the police for their effective and courageous response".

The incident caused major delays to trains at the station in the early morning rush, according to the live departure board of operator SNCF. (AFP)