PARIS (CBS News/CBSDC/AP) — The manhunt for two men suspected in the massacre at a satirical newspaper’s Paris headquarters appeared to be honing in on its targets northeast of the French capital Thursday.

The two suspects – one a former pizza deliveryman who had a prior terror conviction and a fondness for rap – should be considered “armed and dangerous,” French police said in a bulletin.

By Thursday afternoon, authorities focused their search around the towns Villers-Cotterets and Crepy-en-Valois northeast of Paris, according to an official with the national gendarme service.

There were reports that the French-Algerian brothers, Cherif Kouachi, 32, and Said Kouachi, 34, wanted in the Charlie Hebdo attack, might have been traced to Crepy-en-Valois, but an Interior Ministry official denied the suspects were cornered there.

According to the Interior Ministry, 88,000 security forces have been deployed in the manhunt, including 50,000 policemen. Nine people were in custody and 90 witnesses have been interviewed, said French Interior Minister Bernard Cazeneuve.

Police were also seen searching homes in the village of Corcy, near the town of Longpont, further to the east but in the same region as Crepy-en-Valois. Most of the police activity reported Thursday was along or near to a highway running northeast from central Paris, the N2.

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An official at the town’s City Hall told CBS News that for about an hour on Thursday she heard police sirens and saw helicopters flying overhead, but that everything had gone quiet since. Photos from the town showed a large police presence.

Earlier the brothers were reportedly spotted in a grey Renault Clio — a vehicle matching the description of one linked to the suspects on Wednesday — in the Aisne area, in northern France. French news agency AFP said the two men had been “located” in northern France.

Other reports suggested the men were driving toward Paris from the northeast. Police confirmed to CBS News that personnel had established checks at all major highway entry points into the capital city.

One of the reported sightings was by a gas station employee, who told a television station two men stole gas and other items before driving off. He said they were carrying weapons. Police swarmed the site while helicopters hovered above, but officials said later the newspaper attackers were not there.

French President Francois Hollande – joined by residents, tourists and Muslim leaders – called for tolerance after the country’s worst terrorist attack in decades. At noon, the Paris metro came to a standstill and a crowd fell silent near Notre Dame cathedral to honor Wednesday’s victims.

“France has been struck directly in the heart of its capital, in a place where the spirit of liberty – and thus of resistance – breathed freely,” Hollande said.

Hollande ordered flags flown at half-staff, and the Eiffel Tower will switch off its lights and shroud tourists in dark.

France’s prime minister said the possibility of a new attack “is our main concern” and announced several overnight arrests. Tensions ran high in Paris, where 800 extra police patrolled schools, places of worship and transit hubs. Britain increased its security checks at ports and borders.

Earlier Thursday, a female police officer was killed and another man wounded in a shooting in the southern Paris suburb of Montrouge, which came amid theongoing manhunt for two heavily armed brothers — one with possible links to al Qaeda — suspected in the methodical killing of 12 people at the Charlie Hebdo newspaper the day before.

The Paris prosecutor’s office handling the investigation into the shooting said there was no apparent connection between the Charlie Hebdo attack and the Montrouge incident.

Charlie Hebdo has ridiculed political and religious figures for years and had been previously attacked by Muslim extremists for artistic depictions of the Prophet Muhammad.

Two police officers were among the dead in the Wednesday attack on Charlie Hebdo. The Independent reports that one of the officers killed, 42-year-old Ahmed Merabet, was Muslim. He is believed to be the officer who was executed in the street as he was pleading for his life.

French Prime Minister Manuel Valls said earlier Thursday that there had been “several arrests” overnight in the hunt for the two suspects still on the loose after the Charlie Hebdo attack.

A third suspect in that attack, Hamyd Mourad, 18, surrendered Wednesday evening at a police station in Charleville-Mezieres, a small town in France’s eastern Champagne region, said Paris prosecutor’s spokeswoman Agnes Thibault-Lecuivre. She did not offer details on Mourad’s relationship to the men, but said he turned himself in because he heard his name on the news in connection with the attack.

In an interview with RTL radio Thursday, Valls said preventing another attack was “our main concern,” as he explained why authorities released photos of the two men still at large, along with a plea for witnesses to come forward.

Valls says the Kouachi brothers where known and followed by French secret services. One or both of them had traveled to Iraq or Syria in recent years, and the younger brother was convicted previously, in 2008, for recruiting young men to go and fight in Iraq.

A senior U.S. intelligence source told CBS News that Mourad is the brother in law of the two brothers. The Kouachis are believed to have been connected to al Qaeda in Iraq (which later becameISIS) and have current links in Yemen, where one of them visited in 2011.

Al Qaeda in the Arabian Peninsula (AQAP), the branch of the terror network considered to represent the most immediate threat to the U.S. and other Western nations, is based in Yemen. A witness to the attack on Wednesday said one of the men claimed to be acting on behalf of “al Qaeda in Yemen” during the shooting.

CBS News’ Clarissa Ward reports a total of seven people were taken into police custody as of Thursday morning for questioning in relation to the attack on Charlie Hebdo. Among those being held were Mourad, Said Kouachi’s wife, sister and his sister’s husband.

Ward says the search centered on the city of Reims, where the Kouachis were believed to have been living. The two men were allegedly identified after one of them left their ID card in the abandoned get-away car.

Meanwhile, Patrick Pelloux, a writer for the satirical magazine, said Charlie Hebdo would publish a new edition on Jan. 14.

CBS News has learned that in the aftermath of the attack on Charlie Hebdo, Attorney General Eric Holder will travel to Paris to attend an International Ministerial meeting on January 11, convened by the French Minister of Interior. The meetings will include discussions on addressing terrorist threats, foreign fighters and countering violent extremism.

President Barack Obama called Wednesday’s terror attack cowardly and evil.

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