Paris - French forces were on Saturday frantically hunting for the girlfriend of an Islamist gunman as the country mourned 17 dead in three blood-soaked days that shook the nation to its core.After President Francois Hollande warned the threats facing France "weren't over" and Islamist groups issued chilling warnings of fresh attacks, authorities pursued 26-year-old Hayat Boumeddiene, said to be "armed and dangerous".She is the partner of Amedy Coulibaly, killed on Friday when security forces mounted a massive assault on a Jewish supermarket in eastern Paris where he had taken terrified shoppers hostage.Coulibaly, who said he was a member of the Islamic State jihadist group, slaughtered four hostages during the assault and called friends from the scene urging them to stage further attacks.He and Boumeddiene are the prime suspects in the earlier murder of policewoman on Thursday just outside the French capital.Emergency meetingHollande held an emergency meeting of key ministers early on Saturday, hours after the explosive end to twin sieges that also resulted in the death of two brothers who began the terror spree on Wednesday when they massacred 12 at the offices of the Charlie Hebdo satirical weekly in Paris.Interior Minister Bernard Cazeneuve said after the meeting that France was keeping the highest possible security alert level for the greater Paris area.And as France's bloodiest week in decades drew to a close, the mood began to turn to one of grim national reflection with preparations in full swing for what was already being hailed as a "historic" march for national unity, attended by a host of world leaders.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.'Appalling anti-Semitic act' Already reeling from the massacre at Charlie Hebdo two days earlier, the bloodiest atrocity on French soil in half a century, France was rocked by an unprecedented series of attacks on Friday that climaxed in two siege dramas.The massive manhunt for the two Kouachi brothers developed into a car chase and then a tense standoff as they holed up in a printing firm northeast of Paris with a hostage.The small town of Dammartin-en-Goele was transformed into what looked like a war zone, with elite forces deploying snipers, helicopters and heavy-duty military equipment as they surrounded the pair.With all eyes on the siege outside Paris, suddenly explosions and gunfire shook the City of Light itself as Coulibaly stormed a Jewish supermarket on the eastern fringes of the capital.In what Hollande called an "appalling anti-Semitic act", he took terrified shoppers hostage hours before the Jewish Sabbath, killing four.Fiery climaxAs the sun set on the horrified capital, the twin dramas reached a fiery climax.The brothers charged out of the building with guns blazing in a desperate last stand, before being cut down.Within minutes, elite commando units moved against Coulibaly, who had threatened to execute his hostages unless the brothers were released.Coulibaly had just knelt to do his evening prayer when the special forces struck. Explosions rocked the neighbourhood - one lighting up the shopfront in a fireball - and shooting erupted as the commandos burst in."It's war!" shouted a mother as she pulled her daughter away.However up to five people - including a 3-year-old boy - survived hidden inside a refrigerator for five hours, with police pinpointing their location using their mobile phones, prosecutors and relatives said.In the printing firm, the brothers took the manager hostage, later releasing him after he helped Said with a neck wound, while a second man hid beneath a sink upstairs.'Clear failings' As the drama reached its climax, links emerged showing the brothers and Coulibaly were close allies and had worked together.All three had a radical past and were known to French intelligence.Cherif Kouachi, 32, was a known jihadist who was convicted in 2008 for involvement in a network sending fighters to Iraq.His brother Said, 34, was known to have travelled to Yemen in 2011, where he received weapons training from AQAP.It also emerged that the brothers had been on a US terror watch list "for years".Cherif told French TV he was acting on behalf of the Yemen-based al-Qaeda in the Arabian Peninsula while Coulibaly said he was a member of the Islamic State group.Coulibaly, 32 - who met Kouachi in prison - was sentenced to five years in prison in 2013 for his role in a failed bid to break an Algerian Islamist, Smain Ait Ali Belkacem, out of jail.Prime Minister Manuel Valls said the carnage they left in their wake showed there had been "clear failings" in intelligence.The Islamic State group's radio praised them as "heroes" and Somalia's Shebab militants, al-Qaeda's main affiliate in Africa, hailed their "heroic" act.While the immediate danger appeared to have cleared, a chilling new warning came from AQAP whose top sharia official Harith al-Nadhari threatened France with fresh attacks, the SITE monitoring group said."It is better for you to stop your aggression against the Muslims, so perhaps you will live safely. If you refuse but to wage war, then wait for the glad tiding."'We stand with you' As the world rallied to France's side, US President Barack Obama vowed assistance."I want the people of France to know that the United States stands with you today, stands with you tomorrow," Obama said, describing France as America's "oldest ally".Some of France's best-loved cartoonists, as well as two police officers, were killed at Charlie Hebdo, a weekly that infuriated Muslims by repeatedly publishing mocking cartoons of the Prophet Mohammed.Also on Friday, the mourning capital shone the words "Paris Est Charlie" (Paris Is Charlie) on the Arc de Triomphe monument, playing on the phrase "I Am Charlie" (Je Suis Charlie) that has taken centre stage at rallies around the globe and featured heavily on social media.