(Bloomberg) -- Paris was on edge as a shooting south of the citytoday claimed the life of a policewoman and the hunt intensifiedfor two of the perpetrators of yesterday’s massacre at satiricalmagazine Charlie Hebdo.

As hundreds of police and soldiers patrolled airports, schoolsand cultural sites like the Eiffel Tower and the Louvre, a suspectpackage at the Gare du Nord resulted in the evacuation of thestation and streets around the Presidential Elysee Palace wereblocked by security officers in body armor.

Rumors of armed men, shootouts, explosions and bomb threats madetheir rounds on social media and over the airwaves, and policeguarded the main gateways to the capital, creating an atmosphere ofa city under siege. One of the deadliest attacks since World War IIat the heart of Europe by suspected Islamist assailants is bringingwith it an environment of fear to France and the region.

“We are confronting an exceptional risk that can lead at anymoment to other instances of violence,” Interior Minister BernardCazeneuve said on Europe 1 radio.

The attacks threaten to stoke Islamophobia in a country that hasthe biggest Muslim population in Europe and may bolster support forthe anti-immigration National Front party. They prompted othercountries to bolster security, with the U.K. stepping up bordersecurity and Spain raising its terror alert.

Around the world, tens of thousands of people rallied yesterdayin support of the victims, gathering at public squares and Frenchembassies from New York to Hong Kong. In Paris, more than 10,000people thronged the place de la Republique, holding candles andsigns that said “Je suis Charlie” -- I am Charlie.

Armed and Dangerous

At least 12 people died at the Charlie Hebdo office ineastern Paris, and 11 people were injured. No link has beenestablished between those killings and today’s shootout justoutside the capital, police said.

In today’s incident, an unarmed policewoman was killed and atraffic agent was injured after an assailant shot them with apistol and an automatic weapon. The attacker remains at large.

In another troubling twist, a shot was fired at a mosque in LeMans today and four plaster grenades thrown into its courtyard.

In the Charlie Hebdo case, Cazeneuve said seven peopleare being questioned, with the two suspected perpetrators --brothers Said Kouachi, 34, and Cherif Kouachi, 32, -- on the run.They are armed and dangerous, police said.

The youngest suspect in the attack turned himself in, aspokeswoman for the Paris prosecutor said. The 18-year-oldhigh-school student may have been confused with another person.Classmates tweeted that yesterday that he was at his school inCharleville-Mezieres, 230 kilometers (135 miles) from Paris, andthat he has nothing to do with radical Islam.

Police Protection

Police had seen no indication that the suspected assailants wereplanning an assault, according to Cazeneuve. Cherif Kouachi hadserved time in prison for participating in a jihadist recruitmentcell.

Jean-Louis Bruguiere, a former anti-terrorist prosecutor, saidin an interview that Islamic radicals once came out oforganizations whose e-mails and money transfers could be tracked,or were radicalized in underground mosques that could be monitored.Now they are recruited through social media.

France is on the highest terrorist alert, with protectionextended to places of worship and media outlets.

Yesterday’s assault was carried out by two masked menbrandishing AK-47 Kalashnikov rifles, with at least one shouting“Allahu Akbar,” or “God is great” in Arabic.

‘Exceptional Barbarity’

“France is in a state of shock after this terrorist attack,”said President Francois Hollande. “An act of exceptional barbarityhas been perpetrated against a newspaper, against liberty ofexpression, against journalists.”

Thousands of people flocked into town squares across France lastnight to defend what they said were values dear to them.

“I came here to show we don’t cede to terror,” said ElieBenchimol, 23, an economics student who was at the Place de laRepublique in Paris. “France must continue to define itself as acountry of freedom of expression and rule of law.”

The dead included eight journalists, a guest at the weekly, amaintenance man and two policemen. The magazine’s most renownedcartoonists -- Cabu, Charb, Tignous and Wolinski -- were amongthose killed.

France’s last major terrorist violence came in 1995, whenbombings struck public places between July and October, includingthe Saint Michel metro station in the heart of Paris. Bombs alsoexploded in the Place de l’Etoile. In all, eight were killed andabout 200 were injured. The bombings were blamed on an Algerianrebel group.

In 2012, Mohammed Merah, a 23-year-old Frenchman of Algeriandescent, murdered seven people, including three children and ateacher at a Jewish school in Toulouse.

“We can’t accept this madness,” Dalil Boubakeur, the ParisMosque’s rector, said yesterday. “We want to live in peace.”

--With assistance from Tara Patel and FabioBenedetti-Valentini in Paris.

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