PARIS - France vowed to combat terrorism with "a cry for freedom" in a giant rally for unity today after three days of bloodshed that horrified the world. Police searched for a woman linked to the three al-Qaida-inspired attackers, but a Turkish official said she appears to have already slipped into Syria.

The rally today is also a huge security challenge for a nation on alert for more violence, after 17 people and three gunmen were killed over three days of attacks on a satirical newspaper, a kosher supermarket and on police that have left France a changed land.

Hundreds of thousands of people marched Saturday in cities from Toulouse in the south to Rennes in the west to honor the victims, and Paris expects hundreds of thousands more at today's unity rally. More than 2,000 police are being deployed, in addition to tens of thousands already guarding synagogues, mosques, schools and other sites around France.

Unity against extremism is the overriding message for today's rally. Among the expected attendees are the Israeli prime minister and the Palestinian president. The Ukrainian president and Russian foreign minister, And the leaders of Britain, Germany, NATO, the Arab League and African nations. And the French masses, from across the political and religious spectrum.

Top European and U.S. security officials are also holding a special emergency meeting in Paris about fighting terrorism.

The rally "must show the power, the dignity of the French people who will be shouting out of love of freedom and tolerance," Prime Minister Manuel Valls said Saturday.

"Journalists were killed because they defended freedom. Policemen were killed because they were protecting you. Jews were killed because they were Jewish," he said. "The indignation must be absolute and total - not for three days only, but permanently."

Al-Qaida's branch in Yemen said it directed Wednesday's attack against the publication Charlie Hebdo to avenge the honor of the Prophet Muhammad, a frequent target of the weekly's satire.

French radio RTL released audio Saturday of Amedy Coulibaly, speaking by phone from the kosher supermarket where he killed four hostages, in which he lashes out over Western military campaigns against extremists in Syria and Mali. He describes Osama bin Laden as an inspiration.

The focus of the police hunt is on Coulibaly's widow, Hayat Boumeddiene. Police named her as an accomplice of her husband in the shooting of a policewoman and think she is armed.

But a Turkish intelligence official told The Associated Press on Saturday that a woman by the same name flew into Sabiha Gokcen, which is Istanbul's secondary airport, on Jan. 2, and that she resembled a widely distributed photo of Boumeddiene.

Turkish authorities believe she traveled to the Turkish city of Sanliurfa near the Syrian border two days later, according to the official, who added: "She then disappeared."

He spoke on condition of anonymity because he was not authorized to speak on the record.

The French president held an emergency security meeting Saturday and Interior Minister Bernard Cazeneuve said the government is maintaining its terror alert for the Paris region at the highest level while investigators determine whether the attackers were part of a larger extremist network.

Five people are in custody in connection with the attacks, and family members of the attackers have been given preliminary charges.

In a sign of the tense atmosphere, a security perimeter was briefly imposed at Disneyland Paris on Saturday before being lifted, a spokeswoman said, without elaborating.

The prime minister and Muslim and Christian supporters joined Jewish groups in a vigil after sundown Saturday to mourn the four people killed at the kosher market. Israeli Prime Minister Benjamin Netanyahu asked France to maintain heightened security at Jewish institutions even after the return to routine.

Palestinian President Mahmoud Abbas condemned the attacks. Gaza's Islamic Hamas leaders condemned the attack on the satirical newspaper, but pointedly refrained from mentioning the kosher supermarket.