A car has crashed into a police van before bursting into flames around the Champs Elysees area of central Paris, police officials say.
The driver, who was armed, was knocked unconscious and is seriously injured, French media report.
Police say the situation is now under control, and neither law enforcement nor civilians were injured.
France is currently in a state of emergency after being hit by a wave of deadly terror attacks in recent years.
A policeman was shot dead and two others were wounded in an attack on the Champs Elysees in April, just days before the presidential election.
The national police Twitter account had earlier said (in French) that there was an “ongoing police operation”, warning people to respect the security cordon.
French media, quoting police sources, say the act was deliberate.