The youngest of the three suspects in the attack on Charlie Hebdo, a satirical magazine here, has surrendered voluntarily, a media report said.
The 18-year-old suspect may have helped two other suspects to escape, Xinhua quoted police as saying. He surrendered "around 23.00 hours after seeing his name on social media", media reports citing a police source said.
Another source also confirmed that "he was arrested and put in custody".
On Wednesday, Hooded gunmen dressed in black burst into the office of the magazine, killing 12 people in a coordinated strike. The attackers then fled the spot.
The three suspects were later identified and named in a police document circulated to regional forces as Hamyd Mourad, 18, and brothers Said Kouachi, 32 and Cherif Kouachi, 34.
"Two of them are brothers," said Paris Deputy Mayor Patrick Klugman.
Cherif Kouachi was convicted in 2008 of terrorism charges for helping funnel fighters to Iraq's insurgency, and sentenced to 18 months in prison.
During his 2008 trial, he told the court he was motivated by his outrage at television images of torture of Iraqi inmates at the US prison at Abu Ghraib.
Eight journalists, including the magazine's editor, and two policemen were among the dead.