Two of the victims are in grave condition in hospital, BFM TV quoted sources close to the investigation as saying.
There was no immediate word on the identity of the assailant, or his motive.
Ambulances and police vehicles lined a road approaching the park, according to a Reuters journalist at the scene.
In the past four years, the French capital has been rocked by major attacks resulting in mass casualties.
In October last year, four people were stabbed to death at the Paris police headquarters by Mickael Harpon, an IT specialist working for the police. Prosecutors said that attacker, who was shot dead by police, had come under the sway of radical Islamists.
Coordinated bombings and shootings by Islamist militants in November 2015 at the Bataclan theatre and other locations around Paris killed 130 people in the deadliest attacks in France since World War Two.
LEAVE A COMMENT Your email address will not be published. Required fields are marked*
Nearly 100 whales die after mass stranding in New Zealand
Four dead as migrant boat capsizes off Canaries
Notre-Dame reaches milestone as damaged scaffolding is cleared
Outrage over police removal of migrants
Russia caught US warship in its waters, chased it off, says defence ministry
UK considers withdrawing judges from top Hong Kong court
Covid-19 vaccines offer hope as world leaders plan for future
Worldwide Covid cases cross 58mn
AstraZeneca's 'vaccine for the world' can be 90% effective