France has declared a national state of emergency and has closed its borders after at least 120 people were killed in gun and bomb attacks in Paris.
Some 80 people are reported to have died at the Bataclan concert hall in central Paris.
Gunmen took many hostages there before being overpowered by police.
Others died in a reported suicide blast near the Stade de France and gun attacks on city centre restaurants. Seven attackers are reported killed.
Paris residents have been asked to stay indoors and about 1,500 military personnel are being deployed across the city.
The deadliest attack appears to have targeted the Bataclan concert hall, with unconfirmed reports saying that some concert-goers were shot after being taken hostage. Police sources told AFP news agency that at least 100 people had died there.
Speaking after arriving at the concert hall, President Francois Hollande said the attackers would be fought "without mercy".
At least three gunmen are reported to have been killed at the venue.
Bataclan concert venue, 50 boulevard Voltaire, 11th district - hostages held
Le Carillon, 18 rue Alibert, 10th district - gun attack
Le Petit Cambodge, 20 rue Alibert, 10th district - gun attack
La Belle Equipe, 92 rue de Charonne, 11th district - gun attack
Near Stade de France, St Denis, just north of Paris - reported suicide bombing near venue as France v Germany football match played
Reports of gunfire at at least two other sites
US President Barack Obama spoke of "an outrageous attempt to terrorise innocent civilians".
UK PM David Cameron said he was shocked and pledged to do "whatever we can to help".