France’s interior minister called for “extreme vigilance” after the attacks.

Bernard Cazeneuve said after an emergency security meeting on Saturday that the government is deploying hundreds of troops in addition to thousands of police and other security forces. “We are exposed to risks,” he said, and France is maintaining its terror alert system at the highest level in the Paris region.

President Francois Hollande had convened the meeting to discuss how to thwart any new attack.

Elite French police had stormed a printworks on Friday, killing two brothers wanted for shooting dead 12 people during an ambush on the offices of satirical magazine Charlie Hebdo. 

An apparent accomplice involved in two separate sieges was also killed when police stormed the Jewish supermarket where he took hostages.

Explosions rocked a small printing firm in the village of Dammartin-en-Goele, northeast of Paris and only 12 kilometres from the Charles de Gaulle airport. Smoke poured from the building after the heavily armed forces mounted their assault as night fell.

The brothers, Cherif and Said Kouachi, both in their early 30s, along with accomplice Amedy Coulibaly had an arsenal of weapons and had set up booby traps, according to Paris chief prosecutor Francois Molins.

He said they had a loaded M82 rocket launcher, two Kalashnikov machine guns and two automatic pistols on them.

The two brothers,  launched a desperate escape bid, charging out of the building firing at the security forces before being shot down, a security source said. In thick fog, a helicopter landed on the building’s roof, signalling the end of the assault.

The hostage they had taken was safe, an official said.

DON'T MISS: Revelations emerge about Charlie Hebdo brothers' path to jihad

Before his death, one of the Kouachi brothers told a television station he had received financing from an al-Qaeda preacher in Yemen.

"I was sent, me, Cherif Kouachi, by al-Qaeda of Yemen. I went over there and it was Anwar al-Awlaki who financed me," he told BFM-TV by telephone, according to a recording aired by the channel after the siege was over.

Al-Awlaki, an influential international recruiter had been killed in September 2011 in a drone strike. Kouachi’s brother Said had also met al-Awlaki during a stay in Yemen in 2011.

One witness described coming face-to-face at the printing firm with one of the suspects, dressed in black, wearing a bullet-proof vest and carrying what looked like a Kalashnikov.

The salesman told France Info radio that one of the brothers said: "Leave, we don't kill civilians anyhow."

"On the body of one of the terrorists, the demining teams also found a grenade that had been positioned as a trap," said prosecutor Molins.

Meanwhile, in the east of Paris, gunfire erupted as police stormed a Jewish store, where at least one armed assailant had seized five hostages after two people were killed in a gun battle.

The gunman was also killed, security sources said, as terrified hostages were seen running out of the store.

Coulibaly had attacked police forces with a Kalashnikov assault rifle and a "Skorpion" military pistol. After he was shot, police found two Russian-made Tokarev pistols, two machine guns, a bullet-proof vest and ammunition in the kosher supermarket.

"The supermarket had also been booby-trapped," Molins said, noting that Coulibaly had placed 15 explosive sticks and one detonator in the supermarket.

The hostage-taker in the eastern Porte de Vincennes area of Paris was suspected of gunning down a policewoman in southern Paris on Thursday and knew at least one of the gunmen.

French police released mugshots of the man, Coulibaly, 32, as well as a woman named as 26-year-old Hayat Boumeddiene, also wanted over the shooting of the police officer. The woman, said to be Coulibaly's wife, remains on the run.

Coulibaly had also called BFM-TV to claim allegiance to Islamic State, saying he wanted to defend Palestinians and target Jews.

Coulibaly said he had jointly planned the attacks with the Kouachi brothers, and police confirmed they were all members of the same Islamist cell in northern Paris.

The dramatic climax to the two stand-offs brought to an end more than 48 hours of fear and uncertainty in the country that began when the two brothers slaughtered 12 people at Charlie Hebdo, a satirical magazine, in the bloodiest attack on French soil in half a century.

The Porte de Vincennes area was swamped with police who shut down the city's ringroad as well as schools and shops in the area.

Residents were ordered to stay indoors.

Ahead of the stand-off, police had already exchanged fire with the pair - orphans of Algerian origin - in a high-speed car chase.

Schools in the area were evacuated and residents barricaded themselves indoors as the high-profile standoff with police unfolded.

Prior to the standoff, the suspects had hijacked a car from a woman who said she recognised the brothers.

The spectacular attacks came as it emerged the brothers had been on a US terror watch list "for years".

French authorities mobilised a force of nearly 90,000 after Wednesday’s attack on Charlie Hebdo, a weekly that has long courted controversy by mocking Islam and other religions along with political leaders.

And as fears spread in the wake of the attack, the head of Britain's domestic spy agency MI5 warned that Islamist militants were planning other "mass casualty attacks against the West" and that intelligence services may be powerless to stop them.

As a politically divided and crisis-hit France sought to pull together in the wake of the tragedy, the head of the country's Muslim community - the largest in Europe - urged imams to condemn terrorism at Friday prayers.

In a highly unusual step, French President Francois Hollande met far-right leader Marine Le Pen at the Elysee Palace later yesterday, as France geared up for a "Republican march" tomorrow expected to draw hundreds of thousands.

Hollande said France "faced down" Islamists who were behind the deaths of 17 people in three days of attacks but still remains threatened.

Hollande said "these fanatics have nothing to do with the Muslim religion" - a message aimed at preventing a backlash against France's Muslim community, Europe's biggest, which is estimated at over four million.

He called the hostage-taking in Paris, which took place in a Jewish supermarket in the capital's east, "an appalling anti-Semitic act".

Interior Minsiter Bernard Cazeneuve announced that a total of 88,000 security forces were mobilised across the country and that an international meeting on terrorism would take place in Paris on Sunday.

Meanwhile, questions mounted as to how a pair well-known for jihadist views could have slipped through the net and attack .

Cherif Kouachi, 32, was a known jihadist convicted in 2008 for involvement in a network sending fighters to Iraq.

READ MORE: France 'faced down' attacks but still under threat says Hollande

Said, 34, has been "formally identified" as the main attacker in Wednesday's bloodbath. Both brothers were born in Paris to Algerian parents.

A senior US administration official told Agence France-Presse that one of the two brothers was believed to have trained with Al-Qaeda in Yemen, while another source said that the pair had been on a US terror watch list "for years".

The brothers were barred from flying into the United States, the officials said.

The Islamic State group's radio praised them as "heroes" and Somalia's Shebab militants, al-Qaeda's main affiliate in Africa, praised the massacre as a "heroic" act.

Refusing to be cowed, the controversial magazine plans a print run of one million copies instead of its usual 60,000, as journalists from all over the French media landscape piled in to help out the decimated staff.

"It's very hard. We are all suffering, with grief, with fear, but we will do it anyway because stupidity will not win," said columnist Patrick Pelloux.