Elite French police stormed a printworks and a Jewish supermarket on Friday, killing two brothers wanted for the Charlie Hebdo attack and an apparent accomplice who had taken hostages in two separate sieges that traumatised France.

Paris: Elite French police stormed a printworks and a Jewish supermarket on Friday, killing two brothers wanted for the Charlie Hebdo attack and an apparent accomplice who had taken hostages in two separate sieges that traumatised France.

Meanwhile reports suggested that four hostages at the supermarket were killed.

Explosions rocked a small printing firm in the village of Dammartin-en-Goele, northeast of Paris, and smoke poured from the building as the heavily armed forces mounted their assault as night fell.

The two Islamists launched a desperate escape bid, charging out of the building firing at the security forces before being cut down in their tracks, a security source said.

Meanwhile, in the east of Paris, gunfire erupted as police stormed the 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.

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 in the bloodiest attack on French soil in half a century.

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

French police released mugshots of the man, Amedy Coulibaly, 32, as well as a woman named as 26-year-old Hayat Boumeddiene, also wanted over the shooting of the policewoman.

The Porte de Vincennes area in eastern Paris 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.

In Dammartin-en-Goele, only 12 kilometres from Paris's main Charles de Gaulle airport, French elite forces had deployed snipers on roofs and helicopters buzzed low over the small printing business where the Charlie Hebdo suspects had been cornered early today.

Police sources said there was a "connection" between the supermarket gunman and Cherif and Said Kouachi, accused of carrying out France's bloodiest massacre in half a century at Charlie Hebdo.

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

One witness described coming face-to-face at the printer's 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'."

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

One 60-year-old choked back tears as she said how elite forces burst into the shop where her daughter works and ordered them to take cover.

"My daughter told me: 'Don't be scared mummy, we're well protected. She was calm but me, I'm scared. I'm really scared," said the woman.

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".

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.

Wednesday's bloodbath at Charlie Hebdo, which had repeatedly lampooned the Prophet Mohammed, has sparked a global chorus of outrage, with impromptu and poignant rallies around the world in support of press freedom under the banner "jesuischarlie" (I am Charlie).

US President Barack Obama was the latest to sign a book of condolence in Washington with the message "Vive la France!" as thousands gathered in Paris on a day of national mourning yesterday, and the Eiffel Tower dimmed its lights to honour the dead.

And 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, President Francois Hollande met far-right leader Marine Le Pen at the Elysee Palace later today, as France geared up for a "Republican march" on Sunday expected to draw hundreds of thousands.

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.

Nine people had already been detained as part of the operation, Cazeneuve said. Meanwhile, questions mounted as to how a pair well-known for jihadist views could have slipped through the net and attack Charlie Hebdo.

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

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 AFP 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 both flagged in a US database as terror suspects, and also on the no-fly list, meaning they 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.

AFP