Paris, Jan 8 (IANS/EFE): One of the three suspects believed involved in the massacre at the French satirical weekly “Charlie Hebdo” has surrendered to police in the town of Charleville-Mezieres near the border with Belgium, authorities said Thursday.

Hamyd Mourad, 18, surrendered after allegedly collaborating in the attack carried out by brothers Said and Cherif Kouachi, according to police who have launched a country-wide dragnet for the pair.

In the attack, two masked gunmen burst into the magazine's Paris office Wednesday, killing 12 people, including the editor of “Charlie Hebdo” and three acclaimed cartoonists, and wounding more than 20 other people before making a well-planned getaway.

“Charlie Hebdo” had been the target of attacks in the past by Islamists deeply angered by its satirical treatment of the Prophet Muhammad and the Muslim religion.

Mourad gave himself up shortly before midnight Wednesday after seeing his name circulating on social network websites, according to French press reports.

Meanwhile, the Metronews daily reported that Cherif Kouachi was tried in 2005 for being part of a cell that sends jihadis to Iraq.

He was sentenced to three years in jail but served only half the term.

French Prime Minister Manuel Valls said Thursday that several people were arrested late Wednesday in Paris.

"Several (suspects) were held overnight," Valls told RTL radio, adding that preventing another attack "is our main concern".

The French government has raised its terrorist alert to the highest level and has mobilised more than 3,000 members of the security forces in the search operation for the Kouachi brothers.