The Paris police chief has ordered stepped up security in the French capital for the Christmas and New Year's holidays, mobilizing more than 1,550 officers.
Extra police already were patrolling train stations, commercial centers and gathering areas such as the famed Champs-Elysees avenue.
The most frequented religious establishments, from churches to mosques, also were getting special attention, a police headquarters statement said.
Police were to be especially vigilant at Christmas and New Year's, although extra security would be in place until Jan. 15.
Unrest marked by arson attacks that spread from a poor Paris suburb around France in early November, as well as the threat of terrorism, have heightened concerns for security.
On Monday, counterterrorism agents conducted a major sweep around the Paris region and detained more than 20 people allegedly belonging to a suspected Islamic extremist network.