This article has been updated. An editor’s note has been appended.

As French authorities continued hunting overnight for two men suspected in the killing of 12 people Wednesday at the Paris offices of satirical news magazine Charlie Hebdo, a police officer was fatally shot in a Paris suburb early Thursday. A spokeswoman for the prosecutor’s office later confirmed the female officer’s death, adding that the fatal shooting was not being treated as a terrorist attack and was not believed to be connected to Wednesday’s Charlie Hebdo massacre.

The Associated Press and others reported late Wednesday night that the third terrorist attack suspect, identified as 18-year-old Hamyd Mourad, turned himself into the police. French police identified the other two suspects still at large as brothers Saïd Kouachi and Chérif Kouachi, both French and in their 30s, according to NBC News. Chérif Kouachi was convicted in 2005 of terrorism charges related to fighting in Iraq and sentenced to a year and a half in prison.

There were reports late Wednesday of a raid in Reims, France, a city northeast of Paris. Earlier Wednesday, two senior U.S. counterterrorism officials told NBC News’ Pete Williams that one of the suspects in the Paris attack had been killed and the remaining two were in custody. However, the officials now say the information that was the basis of that account cannot be confirmed, and in fact the manhunt continued.

Several people were detained overnight, French Prime Minister Manuel Valls said, according to the AP.

French police released an appeal for help in the search for two of the suspects, along with photos of the men. “We are calling on everyone with any information to help locate the two individuals in the photos to contact the Judicial Police of Paris,” the police said in a statement. “These men are suspected to be armed and dangerous, They are wanted by the authorities in connection with the investigation into the terror attack at the offices of the Charles Hebdo magazine.”

Two people, including a traffic cop, were shot early Thursday in a Paris suburb, NBC News reported, but it was unclear whether there was a link to the earlier Charlie Hebdo attack.

France awoke Thursday to a national day of mourning after the shootings, which French President Francois Hollande called a “terrorist attack.” Hollande ordered flags to be flown at half-staff and said there would be a moment of silence Thursday at noon local time. “We need to stop the attackers, try them, and very severely punish them,” the president said Wednesday, adding, “Our best weapon is our unity.”

Two masked gunmen armed with Kalashnikov assault weapons stormed the offices of Charlie Hebdo Wednesday morning, killing 12 people. The attackers killed an employee stationed on the first floor before breaking into an editorial staff meeting taking place upstairs, according to Paris prosecutor Francois Molins. They yelled “Allahu Akbar” — or “God is great” — before fleeing to a black Citroen parked outside, he added.

Of the 12 dead, the 10 killed included one police officer, one guest, and eight journalists, Molins said at a press conference on Wednesday. In addition, one maintenance personnel and another officer, who engaged the group as they fled, were killed. Eleven others were wounded, four of whom were in critical condition. Molins added that the attackers headed north from the Charlie Hebdo offices, abandoned the vehicle they fled in, and carjacked a Renault Clio.

In response to the attack, France raised its threat level and increased security at other media organizations, shops and places of worship.

A senior U.S. counter-terrorism official told NBC News they had no confirmation of any claim of responsibility for the attack. “We cannot confirm that ISIS or AQAP or any other group is responsible,” the official said. There was no known connection between the suspects and people in the U.S., NBC News’ Pete Williams reported Wednesday evening. Nor were there any specific threats against the U.S. related to the attack, according to Williams.

view photo essay The world mourns after Charlie Hebdo attack France's capital and the world have come together to share support for Charlie Hebdo.

“We will find the people who did this,” Hollande said in a statement. He met with his inner cabinet about the crisis at the presidential residence Wednesday. Later in the day, the president added that he would hold a special meeting of the presidents of the chambers of the national assembly on Thursday.

“No barbaric act will ever extinguish the freedom of the press,” Hollande added in a later tweet. “We are a united country.”



Molins said there were three exchanges of gunfire and a policeman died in the final burst. Anders Lund, who said he lives about 200 yards from the magazine’s office, told msnbc’s Jose Diaz-Balart that he “noticed a ton of policemen, ambulance, and people were scared, confused” after hearing loud gunshots.

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In Washington, President Barack Obama strongly condemned the attack. ”I think that all of us recognize that France is one of our oldest allies, our strongest allies,” he said in a statement. Obama added that “our counterterrorism cooperation with France is excellent. We will provide them with every bit of assistance that we can going forward.”

Obama offered Hollande U.S. resources to help “identify, apprehend and bring to justice the perpetrators and anyone who helped plan or enable this terrorist attack,” according to a White House readout of a call Wednesday between the two leaders.

The offices of Charlie Hebdo are not far from the U.S. Embassy in Paris. There “are no plans to close or limit access to the U.S. Embassy in Paris or other diplomatic facilities in France,” the embassy tweeted. Flags at the French Embassy in Washington, D.C., were flown at half mast on Wednesday in response to the tragedy. Meilleurs vœux, au fait. pic.twitter.com/a2JOhqJZJM — Charlie Hebdo (@Charlie_Hebdo_) January 7, 2015

Charlie Hebdo has long courted controversy with satirical attacks on political and religious leaders. Some Muslims interpret the Quran as prohibiting visual depictions of the prophet. In 2012, France was forced to temporarily close its embassies and schools in more than 20 countries amid fears of reprisals after the magazine printed cartoons of Muhammad. The Charlie Hebdo offices were also firebombed in 2011 after publishing a caricature of the prophet on its cover.

As a result of the prior attack and ongoing threats to the magazine, police officers had been permanently assigned to protect the magazine’s offices and were on site Wednesday morning. The two officers engaged the gunmen and were killed in the attack.

The publication’s most recent tweet was a cartoon of Abu Bakr al-Baghdadi, the leader of the so-called Islamic State of Iraq and Syria. The text in the cartoon translates to: “Best wishes, by the way.”

Secretary of State John Kerry on Wednesday emphasized the need to protect press freedom. “What [terrorists] don’t understand is they will only strengthen the commitment to that freedom and our commitment to a civilized world,” he said.

Wednesday’s shooting is one of the worst terror attacks on French soil. In March 2012, seven people were killed in three gun attacks targeting French soldiers and Jewish civilians in Montauban and Toulouse, while a string of bombings in 1995 killed eight and injured more than 100.

Muslim leaders in France, as well as in the U.S., condemned Wednesday’s violence. “This extremely grave barbaric action is also an attack against democracy and the freedom of the press,” the French Muslim Council said in a statement.

Britain’s Prime Minister David Cameron said “the murders in Paris are sickening,” adding on Twitter that the United Kingdom stands with France in its fight against terrorism.

There was an international outpouring of support for France and freedom of the press. On Twitter, #jesuischarlie was trending worldwide. Journalists, students and many of the city’s residents were photographed holding signs bearing the slogan, which means “I am Charlie.” The message has flooded the streets of Paris in the form of homemade placards, as well as professionally printed signs and stickers. As night fell, crowds gathered for candlelight vigils in memory of those killed. An illuminated sign atop a monument in Paris’ Plaza de la Republique stated, “Not afraid.”

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“Bernard Maris was a cultured, kind and very tolerant man. He will be much missed,” said Christian Noyer, governor of the Bank of France.

Author Salman Rushdie, whose novel “The Satanic Versus” prompted Iran’s Ayatollah Khomeini to issue a fatwa against him in 1989, commented on the Paris shooting.

“Religion, a mediaeval form of unreason, when combined with modern weaponry becomes a real threat to our freedoms,” he said in a statement. “This religious totalitarianism has caused a deadly mutation in the heart of Islam and we see the tragic consequences in Paris today. I stand with Charlie Hebdo, as we all must, to defend the art of satire, which has always been a force for liberty and against tyranny, dishonesty and stupidity.”

Editor’s note: Earlier Wednesday, two senior US counterterrorism officials told NBC News that one of the suspects in the Paris attack had been killed and the remaining two were in custody. However, the officials now say the information that was the basis of that account cannot be confirmed.