The two main suspects in the Islamist attack on Charlie Hebdo magazine in Paris are said to have robbed a service station in the north of France.

They stole food and petrol, firing shots as they struck at the roadside stop near Villers-Cotterets in the Aisne region, French media report.

France has observed a minute’s silence for the 12 people killed at the office of the satirical magazine.

Earlier in the day, a gunman shot dead a policewoman south of Paris.

A second person was seriously injured in the attack in Montrouge, after which the gunman fled.

It is unclear if the attack is related to the pursuit of prime suspects Cherif and Said Kouachi.

According to the manager of the service station that was robbed on the RN2 road in Aisne at about 10:30 (09:30 GMT), the attackers fit the description of the two men, and were heavily armed with Kalashnikovs and rocket-propelled grenade launchers.

They are said to have driven off in the direction of Paris in a Renault Clio car, apparently the same vehicle hijacked in Paris soon after the Charlie Hebdo attack.

According to French commercial channel BFMTV, police are monitoring all of the main entry roads into the capital.

Meanwhile, the lawyer for Charlie Hebdo, Richard Malka, confirmed that next week’s edition of the magazine would go ahead on Wednesday and would have a print run of one million, instead of the normal 60,000 copies.

The Victims

• Economist and regular magazine columnist Bernard Maris, 68, known to readers as Uncle Bernard
• Cartoonists Georges Wolinski, 80, and Jean “Cabu” Cabut, 76
• Charlie Hebdo editor and cartoonist Stephane “Charb” Charbonnier, 47, who had been living under police protection since receiving death threats
• Cartoonists Bernard “Tignous” Verlhac, 57, and Philippe Honore, 73
• Mustapha Ourrad, proof-reader
• Elsa Cayat, psychoanalyst and columnist, the only woman killed
• Michel Renaud, who was visiting from the city of Clermont-Ferrand
• Frederic Boisseau, 42, caretaker, who was in the reception area at the time of the attack
• Police officers Franck Brinsolaro, who acted as Charb’s bodyguard, and Ahmed Merabet, 42, who was shot dead while on the ground

Live updates

French Interior Minister Bernard Cazeneuve warned against jumping to conclusions after the pre-dawn shooting in Montrouge.

The gunman was armed with a machine-gun and a pistol and wore a bullet-proof jacket, police sources told AFP news agency.

A local resident, Ahmed Sassi, described a “scene of panic”. He said he had seen a police officer standing and then a man dressed in dark clothes who ran up and shot the officer “at point black range”.

“I saw the officer fall and a colleague call for help,” Mr Sassi said.

Overnight, seven people believed to be connected to the Kouachi brothers were detained in the towns of Reims and Charleville-Mezieres, as well as in the Paris area.

Cherif Kouachi was sentenced in 2008 to three years in prison for belonging to a Paris-based group sending jihadist fighters to Iraq.

Following the shootings at the magazine, there appear to have been a number of revenge attacks on Muslims reported by French media, though nobody was hurt

• Two shots were fired at a Muslim prayer room in the town of Port-la-Nouvelle in the southern region of Aude on Wednesday evening
• A Muslim family was shot at in their car in Caromb, in the southern region of Vaucluse
• Dummy grenades were thrown during the night at a mosque in Le Mans, western France
• The slogan “Death to Arabs” was daubed on the door of a mosque in Poitiers, central France, during the night
• A blast hit a kebab shop beside a mosque in Villefranche-sur-Saone in central France

We Killed Charlie Hebdo

Paris has been placed on the highest terror alert and extra troops have been deployed to guard media offices, places of worship, transport and other sensitive areas.

On Wednesday, eight journalists – including the magazine’s editor – died along with a caretaker and a visitor when masked men armed with assault rifles stormed the Charlie Hebdo offices during an editorial meeting. Eleven people were also wounded, some seriously.

Two policemen were also killed.

Witnesses say the gunmen shouted “we have avenged the Prophet Muhammad” and “we killed Charlie Hebdo”, as well as “God is Great” in Arabic.

The attackers fled to northern Paris before abandoning their car and hijacking a Renault Clio, police say.

The magazine’s office was firebombed in 2011. It had angered some Muslims by printing cartoons of the Prophet Muhammad as part of its irreverent take on news and current affairs.

People stood in silence in public spaces across France at midday (11:00 GMT) as the bells of Notre Dame cathedral in Paris and churches nationwide tolled in mourning.

Chris, one of those who had gathered on the Place de la Republique in Paris, told the BBC about the impact of a major terrorist attack on France: “It’s just too bad it’s happened. We don’t understand.

“You know, in previous years everyone told us it could happen. It happened in Spain, it happened in Britain, it happened everywhere. But everything is falling on us. The sky is just falling on our heads.”

Vigils were held through the night in Paris and cities worldwide in tribute to the dead. Many demonstrators held up placards reading “Je suis Charlie” (I am Charlie) in solidarity with the victims.

French President Francois Hollande said the country’s tradition of free speech had been attacked and called on all French people to stand together.

Cartoon tributes are circulating on social media, sending out the message of press freedom. One Dutch cartoon plays on 9/11 Twin Towers imagery, showing a plane flying towards two upright pencils.

Thursday’s national day of mourning is only the fifth held in France in the past 50 years.

National Days Of Mourning In France

• 12 November 1970 – Death of former President Charles de Gaulle
• 6 April 1974 – Death of President Georges Pompidou
• 11 January 1996 – Death of former President Francois Mitterrand
• 14 September 2001 – 9/11 attacks on New York and Washington
• 3 April 2005 – Death of Pope John Paul II

Charlie Hebdo attack sequence