The French government said Sunday it was determined to choke off the supply of weapons and disarm criminal gangs, several hours after a man was shot dead in the center of Marseille, the southern city known for its high crime levels.

"Within the next six weeks I will put forward a wide-ranging and extremely aggressive plan to fight against the trafficking and possession of weapons in our country," Interior Minister Bernard Cazenueve told Europe 1 radio.

Three young men, including a former naval signalman, were being held Thursday by France's intelligence services, accused of plotting to kidnap and decapitate a member of the armed forces at a military base.

Interior Minister Bernard Cazeneuve said security forces staged dawn raids on Monday and arrested four people, aged between 16 and 23, who were "planning to commit a terrorist act" at a French military installation.

Police said Monday they came under fire as they rushed into a housing estate in the French city of Marseille after residents alerted them that hooded people had shot "Kalashnikovs" in the air.

The outbreak of violence in La Castellane, an estate known as a drug trafficking hotspot, came just hours before Prime Minister Manuel Valls visited the southern port city to hail the progress made in fighting crime.

The head of Paris' powerful criminal investigation force was charged and immediately suspended late Thursday over allegations that he leaked details of a probe to a fellow top officer who was under inquiry.

Just minutes after the Paris prosecutor's office said it was charging Bernard Petit, the French interior ministry announced his suspension and named Christian Sainte, head of the judicial force for the city of Marseille, as his replacement.

More than 100,000 people gathered across France to pay tribute to the victims of Wednesday's massacre by Islamist gunmen in Paris, as thousands also rallied in other European cities and the "I Am Charlie" hashtag swept the Internet.

With the gunmen still on the loose in Paris after killing 12 people, defiant crowds swarmed into the Place de la Republique, barely a kilometer (half a mile) from the scene of the bloodbath at the Charlie Hebdo satirical weekly.

Four French police officers are being held in custody on suspicion of raping a 34-year-old Canadian woman at their Paris headquarters.

Interior Minister Bernard Cazeneuve confirmed the detentions on Friday and vowed to take "all the necessary measures" if the accusation against the four officers is proven.

Some 7,500 gay rights supporters and activists marched through the French port of Marseille on Saturday at the start of Europride 2013.

Under a banner proclaiming "Europe marches towards equality", they made their way from the city's old port to the beach amid celebrations for the beginning of the 10-day festival devoted to the lesbian and gay cause.

A 27-year-old man has been shot dead in Marseille in a slaying reminiscent of a scene from "The Godfather" that was the 10th murder of its kind in and around the city this year and the 34th since the start of 2012.

Djibril Abbas, who had a record of violent armed robbery and drugs offenses, was shot around 30 times after being ambushed by three men as he left a girlfriend's home in the Bon Secours district of the southern port on Saturday evening, police said.

French football pundit Eric di Meco has eaten a rat after losing an on-air bet about a player.

Three years ago, when Spanish full back Cesar Azpilicueta joined di Meco's old club Marseille, the club's then president Jean-Claude Dessier described the player as "Spain's future right back".

Long plagued by a reputation for gang crime and lawlessness, France's port city of Marseille is hoping its year as the European Capital of Culture will finally give its image a makeover.

The gritty Mediterranean city will kick off the festivities on Saturday with a downtown parade, fireworks and the opening of a slew of exhibitions.