The second hostage-taking in France today — which French President François Hollande called an anti-Semitic attack — ended with the deaths of four hostages and the gunman.

Explosions and gunshots were heard outside the Hyper Cacher kosher supermarket, in the Porte de Vincennes neighbourhood on the eastern edge of Paris, almost simultaneously with a raid counterterrorism police launched at a printing factory north of the city, where two suspects in Wednesday's deadly shooting at the Charlie Hebdo offices in Paris were holed up with a hostage.

The suspects, brothers named Cherif and Said Kouachi, were killed in that standoff.

The gunman in the supermarket attack, identified as Amedy Coulibaly, 32, was named as a suspect in the Thursday morning killing of a French policewoman. He took 19 hostages in the grocery, according to an Israeli official recounting a conversation between Israeli Prime Minister Benjamin Netanyahu and Hollande.

Hostage takers Paris

Amedy Coulibaly, left, was killed by French special forces in the standoff. His alleged girlfriend Hayat Boumeddiene, right, was believed to be involved but her exact role, if any, is not yet known. (EPA)

Paris prosecutor François Molins said Friday evening that Coulibaly killed four hostages immediately upon entering the market. Earlier reports from the scene suggested the hostages were killed after police mounted their raid. 

One police official said Coulibaly opened fire with an automatic weapon in the kosher market after entering and declared, "You know who I am."

During the early hours of the standoff, Coulibaly threatened to kill the remaining hostages if French authorities launched an assault on the two brothers, a police official said.

Coulibaly had attacked police forces with a Kalashnikov assault rifle and a "Skorpion" military pistol, Molins said. After he was shot, police found two Russian-made Tokarev pistols, two machine guns, a bullet-proof vest and ammunition in the kosher supermarket. "The supermarket had also been booby-trapped," he said, noting that Coulibaly had placed 15 explosive sticks and one detonator in the supermarket.​

Some hostages were seen rushing from the market after heavily armed police broke the siege, rescuing 15 people. 

Connections uncovered

Police have uncovered several connections between Coulibaly and the younger of the Kouachi brothers, Cherif, dating back to about 2010, when Coulibaly was sentenced to five years in prison for an abortive attempt to free a man convicted on terrorism-related charges from prison. Smain Ait Ali Belkacem was serving a life sentence for a bombing attack on the Paris rapid transit system in 1995.

Cherif Kouachi was detained in that investigation, but freed later without being tried.

French judicial documents obtained by The Associated Press said Coulibaly and the younger Kouachi travelled with their wives in 2010 to central France to visit Djamel Beghal, who had been sentenced to 10 years in prison on a terrorism-related charge.

According to the judicial documents, a police search of Coulibaly's residence in 2010 turned up a crossbow, 240 rounds of 7.62 mm ammunition, films and photos of him during a trip to Malaysia, and letters seeking false official documents.

Paris attacks: 3 days of fear and violence4:51

In a police interview that same year, Coulibaly identified Cherif Kouachi as a friend he had met in prison and said they saw each other frequently, according to a transcript of the interview obtained by the Journal du Dimanche newspaper and posted on the newspaper's website.

Molins, the Paris prosecutor, said authorities increasingly grew to see links between the attackers after they discovered that Boumeddiene and the companion of one of the Kouachi brothers had exchanged about 500 phone calls.

Coulibaly claimed ties to ISIS

French television station BFM said it spoke with Cherif Kouachi and Coulibaly on the phone in separate conversations shortly before they were killed by police. Coulibaly said the three men were co-ordinating their actions and that he was affiliated with ISIS. The Kouachi brothers claimed allegiances to al-Qaeda in Yemen, however, which is a group at odds with ISIS. 

Police also named Hayat Boumeddiene, 26, as a suspect in Thursday's slaying. She is Coulibaly's wife, and early reports suggested she may have accompanied Coulibaly during the supermarket hostage-taking. Her fate remained unclear, but one police source told Reuters she may not have been inside the market during the standoff. 

France Newspaper Attack

Fifteen hostages were rescued by security forces after they stormed a kosher grocery store on the eastern edge of Paris. (Francois Mori/Associated Press)

She is still wanted by police, who issued a bulletin Friday night asking anyone with information about Boumeddiene to contact them. 

In an afternoon national address, Hollande called for national unity and said the country should remain "implacable" in the face of racism and anti-Semitism.

"It is indeed an appalling anti-Semitic act that was committed," he said of the hostage-taking in eastern Paris. "France has not seen the end of the threats it faces."

With files from Reuters and The Associated Press