A car rammed into a mobile police unit Monday on the iconic Champs-Elysees in central Paris, police said on Twitter.
It was not immediately clear if the ramming was intentional.
About 20 police vans and multiple armed police surrounded a man on the ground.
Authorities advised people to avoid the area.
In April, a man shot at police officers on the Champs-Elysees, killing one officer and wounding two others. Police shot and killed Karim Cheurfi as he tried to escape on the busy tourist boulevard.
Developing story. More to come.