A third French police officer was gunned down Thursday south of Paris as the manhunt for two men suspected in the massacre at a satirical newspaper the day before appeared to hone in on its targets northeast of the French capital.
Interior Minister Berbard Cazeneuve said two people, including a police officer, were gravely wounded in the shooting Thursday in the southern Paris suburb of Montrouge, which came amid the ongoing 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 police officer shot Thursday, a woman, died in hospital of her injuries, a police union confirmed.
There were reports, meanwhile, that the French-Algerian brothers, Said and Cherif Kouachi, wanted in the Charlie Hebdo attack were surrounded by police in a building in Crepy-en-Valois, northeast of Paris.
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. There was no confirmation the Kouchais were there, but photos from the town showed a large police presence.
Earlier they 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 two 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 came in and stole gas and other items before driving off. He said they were carrying weapons.
It was not immediately clear whether Thursday's shooting was linked in any way to the attack on Charlie Hebdo, a newspaper which has ridiculed political and religious figures for years and had been previously attacked by Muslim extremists for artistic depictions of the Prophet Muhammad. Cazeneuve urged people not to jump to conclusions.
Two police officers were among the dead in the Wednesday attack on Charlie Hebdo.
Thursday's shooting happened around 8 a.m. local time (2 a.m. Eastern). Cazeneuve said the officer had stopped to investigate a traffic accident when the firing started. Paris police said the second victim was a street sweeper.
"There was an officer in front of a white car and a man running away who shot," said Ahmed Sassi, who saw the shooting from his home nearby.
He said the shooter wore dark clothes but no mask. "It didn't look like a big gun because he held it with one hand," Sassi said.
Witnesses reported hearing at least five gunshots, but officials did not immediately clarify early reports that two suspects could have been involved in the Montrouge incident. There were no confirmed arrests.
French police identified Cherif Kouachi (left) and his brother Said Kouachi (right), as suspects in the attack on the newspaper Charlie Hebdo that left 12 people dead on Jan. 7, 2015, in Paris, France.
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.