* Police issue photographs of two suspects

* Security stepped up across Paris

* France holds day of mourning

* Charlie Hebdo to print a million copies next week

(Adds Obama visit to French Embassy in Washington, sources
saying suspects were in two U.S. security databases)

By John Irish and Christian Hartmann

CORCY, France, Jan 8 (Reuters) – Armed and masked
anti-terrorism police swooped on woodland villages northeast of
Paris on Thursday in a manhunt for two brothers suspected of
being the Islamist gunmen who killed 12 people at a French
satirical weekly.

A day after the Paris attack, officers carried out
house-to-house searches in the village of Corcy, a few km
(miles) from a service station where police sources said the
brothers were sighted in ski masks. Helicopters flew overhead.

The fugitive suspects are French-born sons of Algerian-born
parents, both in their early 30s, and already under police
surveillance. One was jailed for 18 months for trying to travel
to Iraq a decade ago to fight as part of an Islamist cell.
Police said they were “armed and dangerous”.

United States and European sources close to the
investigation said on Thursday that one of the brothers, Said
Kouachi, was in Yemen in 2011 for a number of months training
with Al Qaeda in the Arabian Peninsula (AQAP), one of the
group’s most active affiliates.

A Yemeni official familiar with the matter said the Yemen
government was aware of the possibility of a connection between
Said Kouachi and AQAP, and was looking into any possible links.

U.S. government sources said Said Kouachi and his brother
Cherif Kouachi were listed in two U.S. security databases, a
highly classified database containing information on 1.2 million
possible counter-terrorism suspects, called TIDE, and the much
smaller “no fly” list maintained by the Terrorist Screening
Center, an interagency unit.

U.S. television network ABC reported that the brothers had
been listed in the databases for “years.”

Dave Joly, a spokesman for the Terrorist Screening Center,
said he could neither confirm nor deny if the Kouachis were
listed in counter-terrorism databases.

On Thursday, U.S. President Barack Obama made an unannounced
visit to the French Embassy in Washington to pay his respects.

He wrote in a condolence book, “As allies across the
centuries, we stand united with our French brothers to ensure
that justice is done and our way of life is defended. We go
forward together knowing that terror is no match for freedom and
ideals we stand for – ideals that light the world.”

In Paris, a policewoman was killed in a shootout with a
gunman wearing a bulletproof vest on Thursday morning, setting a
tense nation further on edge. Police sources were unable to say
whether that incident was linked to the previous day’s assault
at the Charlie Hebdo weekly newspaper, but the authorities
opened another terrorism investigation.

Bewildered and tearful French people held a national day of
mourning. The bells of Notre Dame pealed for those killed in the
attack on Charlie Hebdo, a left-leaning slayer of sacred cows
whose cartoonists have been national figures since the Parisian
counter-cultural heyday of the 1960s and 1970s.

The newspaper had been firebombed in the past for printing
cartoons that poked fun at militant Islam and some that mocked
the Prophet Muhammad himself. Two of those killed were police
posted to protect the paper.

While world leaders described the attack as an assault on
democracy, al Qaeda’s North Africa branch praised the gunmen as
“knight(s) of truth”.

Many European newspapers either re-published Charlie Hebdo
cartoons or lampooned the killers with images of their own.

Searches were taking place in Corcy and the nearby village
of Longpont, set in thick forest and boggy marshland about 70 km
north of Paris, but it was not clear whether the fugitives who
had been spotted in the area were holed up or had moved on.

“We have not found them, there is no siege,” an interior
ministry official in Paris said.

Corcy residents looked bewildered as heavily armed policeman
in ski masks and helmets combed the village meticulously from
houses to garages and barns.

“We’re hearing that the men could be in the forest, but
there’s no information so we’re watching television to see,”
said Corcy villager Jacques.

In neighbouring Longpont, a resident said police had told
villagers to stay indoors because the gunmen may have abandoned
their car there. Anti-terrorism officers pulled back as darkness
fell. The silence was broken by the sound of a forest owl.

Thursday’s shooting of the policewoman on the streets of
Paris’s southern Montrouge district — whether related or not —
caused more fear. Montrouge Mayor Jean-Loup Metton said the
policewoman and a colleague came under fire while responding to
a reported traffic accident. Witnesses said the assailant fled
in a Renault Clio. Police sources said he wore a bullet-proof
vest and had a an assault rifle and a handgun.

A police officer at the scene told Reuters he did not appear
to resemble the Charlie Hebdo shooter suspects.

Prime Minister Manuel Valls, asked on RTL radio whether he
feared a further attack, said: “That’s obviously our main
concern and that is why thousands of police and investigators
have been mobilised to catch these individuals.”

SUSPECT JAILED

Police released photographs of the two suspects, Cherif and
Said Kouachi, 32 and 34. The brothers were born in eastern Paris
and grew up in an orphanage in the western city of Rennes after
their parents died.

The younger brother’s jail sentence for trying to fight in
Iraq a decade ago, and more recent tangles with the authorities
over suspected involvement in militant plots, raised questions
over whether police could have done more to watch them.

Cherif Kouachi was arrested on Jan. 25, 2005 preparing to
fly to Syria en route to Iraq. He served 18 months of a
three-year sentence.

“He was part of a group of young people who were a little
lost, confused, not really fanatics in the proper sense of the
word,” lawyer Vincent Ollivier, who represented Cherif in the
case, told Liberation daily.

In 2010 he was suspected of being part of a group that tried
to break from prison Smain Ali Belkacem, a militant jailed for
the 1995 bombings of Paris train and metro stations that killed
eight people and wounded 120. The case against Cherif Kouachi
was dismissed for lack of evidence.

A third person wanted by police, an 18-year-old man, turned
himself into police in Charleville-Mézières near the Belgian
border late on Wednesday. A legal source said he was the
brother-in-law of one of the brothers. French media quoted
friends as saying he was in school at the time of the attack.

In the wake of the killings, authorities tightened security
at transport hubs, religious sites, media offices and stores.
Police also increased their presence at entry points to Paris.

At Porte d’Orleans, one of the capital’s main gateways, more
than a dozen white police vans lined up the main avenue.
Officers stood guard with bulletproof jackets and rifles.

The defence ministry said it sent 200 extra soldiers from
parachute regiments across the country to help guard Paris.

Tens of thousands of people attended vigils across France on
Wednesday, many wearing badges declaring “Je suis Charlie” in
support of the newspaper and the principle of freedom of speech.

Newspapers in many countries republished Charlie Hebdo
cartoons. Britain’s Daily Telegraph depicted two masked gunmen
outside the doors of Charlie Hebdo saying to each other: “Be
careful, they might have pens.”

Charlie Hebdo’s lawyer Richard Malka said the newspaper
would be published next Wednesday with one million copies
compared to its usual print run of 60,000.

Muslim leaders condemned the shooting, but some have
expressed fears of a rise in anti-Islamic feeling in a country
with a large Muslim population. The window of a kebab shop next
to a mosque in the town of Villefrance-sur-Saone was blown out
by an overnight explosion. Local media said no one was hurt.

(Additional reporting by Valerie Parent, Sophie Louet,
Alexandria Sage, Emmanuel Jarry, Nicolas Bertin, Hannah Murphy,
Ingrid Melander; Writing and editing by Peter Graff, Mark John,
Ralph Boulton, Peter Millership, Crispian Balmer, Toni Reinhold)