French authorities on Saturday were hunting for a woman said to be “armed and dangerous,” who they believe is connected to three days of violence that reached a bloody denouement in twin sieges Friday.

Hayat Boumeddiene, 26, may have fled France ahead of the attacks and may now be in Syria, French media reports said Saturday. The reports, which cited unnamed police sources, raised further questions about the attackers’ connections to organized Islamist militant groups. Boumeddiene, 26, is the partner of Amedy Coulibaly, who on Friday seized a kosher grocery store in eastern Paris, killing four people at the height of pre-Sabbath shopping before being killed himself after an hours-long standoff. A day earlier, he killed a Paris police officer, authorities believe. During the Friday standoff, he said he was affiliated with the Islamic State, which is headquartered in Syria.

With French President François Hollande convening another crisis meeting of his security advisers Saturday, Boumeddiene’s disappearance was a reminder of lapses that allowed a group of homegrown Islamist militants to attack even though they were well-known to authorities.

Boumeddiene “is dangerous insofar as she is the partner of a person who murdered people in a supermarket in cold blood,” said Christophe Crepin, a police union spokesman. “Right now she’s being searched for as a witness. We want to ask her questions to understand what she knows.”

The French reports said that authorities now believe that Boumedienne took a flight from Madrid to Istanbul on Jan. 2. She then reportedly crossed into Syria on Jan. 8, the day her partner is suspected of killing a Paris police officer and a day before he attacked the supermarket.

Hayat Boumeddiene, 26, is wanted for questioning in France. (Getty Images)

In a sign of the continuing security fears, Paris’s Grand Synagogue on Friday did not hold evening Sabbath services for the first time since World War II. All four victims at the kosher grocery store were Jewish, a Jewish organization said Saturday. The French Representative Council for Jewish Institutions said that Yoav Hattab, Philippe Braham, Yohan Cohen and François-Michel Saada had been killed when Coulibaly stormed the store.

It was unclear what role Boumeddiene played in the attacks that started Wednesday, when two brothers and an associate went on a bloody rampage at the Paris offices of a satirical newspaper that had published cartoons mocking Islam. That attack left 12 dead, and France was paralyzed in the aftermath with the killers at large. The two men died Friday after taking a hostage at a printing plant outside Paris. The new timeline would place her outside France well before the attacks.

French security officials said Friday that Boumeddiene was “armed and dangerous” and connected to the separate killing of a police officer a day earlier. They released her name along with that of her partner, Coulibaly, 32, after he took hostages at the kosher grocery store. Paris’s prosecutor also said that Boumeddiene had communicated extensively with the wife of one of the other killers, drawing a line between the coordinated attacks.

On Saturday, French Interior Minister Bernard Cazeneuve said that the country remained on the highest security alert with Boumeddiene at large. A massive demonstration in support of the victims is planned for Sunday, posing another security challenge for French authorities. British Prime Minister David Cameron, Italian Prime Minister Matteo Renzi, German Chancellor Angela Merkel and other world leaders have said they will attend.

French authorities have said that Coulibaly and one of the brothers in the attack on the Charlie Hebdo newspaper were associates who belonged to the same militant network, named for the Buttes Chaumont park in Paris where they exercised. Coulibaly and the brother, Chérif Kouachi, were reportedly radicalized together in prison in 2005 when they met Djamel Beghal, a French Algerian jihadist convicted of plotting to attack the U.S. Embassy in Paris in 2001.

All three men were known to French authorities, and Coulibaly was imprisoned as recently as 2013 over an attempt to break out another Islamist militant from prison. But he was freed and apparently unmonitored as the group plotted the attacks.

The carnage exposed glaring holes in France’s intelligence services as fears mounted in European nations about the consequences of radicalized citizens who might return after fighting in Syria and elsewhere in the Middle East. Thousands of Europeans have gone to the region in recent years, and officials have characterized the developments as the top security threat in Europe. But the Kouachi brothers appear to have traveled to Yemen, not Syria, escaping some of the scrutiny.

French authorities launched a massive dragnet this week following the massacre at the satirical newspaper Charlie Hebdo. Here are the key moments so far. (Jorge Ribas/The Washington Post)

In another sign of the confusion over the attacks, one 18-year-old man who was initially named as a suspect in the Wednesday attack on Charlie Hebdo was released from custody late Friday, law enforcement officials said. The man, Hamyd Mourad, was Chérif Kouachi’s brother-in-law but appears not to have been connected to the attacks, Agence France-Presse reported. The Paris prosecutor general said late Friday that five people remained in custody in connection with the attacks. Crepin, the police union spokesman, said one of those five was Chérif Kouachi’s wife.