The four people killed in the terrorist attack at a kosher supermarket in Paris on Friday were all Jews, the CRIF umbrella group of French Jewish communities said.

CRIF identified the victims of the attack Friday as Yoav Hattab, 21, Philippe Braham, in his 40s, Yohan Cohen, 22, and Francois-Michel Saada, in his 60s.

France deployed hundreds of troops around Paris Saturday, beefing up security on the eve of a march expected to draw more than a million in tribute to 17 victims of a three-day Islamist killing spree – four of them shoppers at a Jewish supermarket.

Fears remained acute and security levels were kept at France's highest level as the girlfriend of one of three gunmen killed in a fiery climax to twin hostage dramas on Friday was still on the loose.

But refusing to be cowed, more than 200,000 poured onto the streets in cities across France in poignantly silent marches paying tribute to those killed in the nation's bloodiest week in more than half a century.

The marches across the country were a taste of what was to come in Paris Sunday, where a major rally will be held for national unity, to be attended by President Francois Hollande and a host of world leaders.

The defense ministry said it was sending another 500 soldiers into the greater Paris area, bringing current numbers to some 1,350 troops.

Yoav Hattab (L) and Yohan Cohen (R) were among four Jews murdered in Friday's brutal attack
Yoav Hattab (L) and Yohan Cohen (R) were among four Jews murdered in Friday's brutal attack Screenshot/Facebook

After Friday's dramatic events, Hollande warned grimly that the threats facing France "weren't over", comments followed by a chilling new threat from a Yemen-based Al Qaeda group.

Security forces were focused on hunting down 26-year-old Hayat Boumeddiene, the "armed and dangerous" partner of Amedy Coulibaly who took terrified shoppers hostage in a Jewish supermarket on Friday, killing four of them.

People laid flowers at the shop as a tribute and one woman attached signs to a police barrier reading: "Je suis Charlie" ("I am Charlie"), "I am police", "I am mourning", "I am Jewish."

Before Coulibaly was killed by elite police in a massive assault on the store, he told journalists he was a member of the Islamic State jihadist group.

Coulibaly and Boumeddiene are the prime suspects in the murder of a policewoman on Thursday just outside the French capital.

That attack further spooked a nation still reeling from the Wednesday assault at the Charlie Hebdo satirical weekly in Paris that saw two gunmen mow down 12 people including some of the country's best-known cartoonists.

In a sombre address after Friday's sieges, Hollande said: "I call on all the French people to rise up this Sunday, together, to defend the values of democracy, freedom and pluralism to which we are attached."

But as leaders urged the country to pull together in grief and determination, questions were also mounting over how the three men – brothers Cherif and Said Kouachi, and Coulibaly – had slipped through the security net after it emerged that all three were known to the intelligence agencies.

And despite calls for political unity, far-right leader Marine Le Pen urged her supporters to attend rallies outside Paris, but not in the capital.

France's darkest week in decades came to an explosive end on Friday after the three gunmen seized hostages in two locations some 30 kilometers (18 miles) apart.

The massive manhunt for the two Kouachi brothers developed into a car chase and then a tense standoff as they took one person hostage in a printing firm. Meanwhile AQAP top sharia official Harith al-Nadhari warned France to "stop your aggression against the Muslims" or face further attacks, in comments released by the SITE monitoring group.

The gunman killed by police on Friday after taking hostages at a Jewish supermarket in Paris told the French BFMTV station he had "coordinated" with the suspected Charlie Hebdo attackers and belonged to the Islamic State (ISIS) group, AFP reported Friday evening.

The French channel managed to speak to Amedy Coulibaly, as well as to one of the two Kouachi brothers suspected behind Wednesday's magazine massacre, before all three were killed in police raids ending two hostage dramas.

Cherif Kouachi, the younger sibling, said that a trip he made to Yemen in 2011 was financed by American-Yemeni radical Anwar al-Awlaki, who was killed in Yemen by an American drone strike in September that year.

While holed up with a hostage at a print works in the tiny town of Dammartin-en-Goele northeast of Paris, Kouachi told BFMTV that they were on a mission from the Yemeni branch of Al-Qaeda, Al-Qaeda in the Arabian Peninsula (AQAP).

Shortly after the Wednesday killing at Charlie Hebdo that left 12 dead, the brothers hijacked a car telling the driver, "Say we are from Al-Qaeda in Yemen."