A man who stabbed two police officials to death at their home in a Paris suburb posted a video online confessing to the killings and pledging loyalty to the Islamic State group. The attacker also had a list of other targets, including rappers, journalists, police officers and public officials.
The French president urged heightened security and vigilance after what he said was "incontestably a terrorist act."
The attack hit the country's raw nerves after Islamic State attacks in November killed 130 people, and as 90,000 security forces are deployed to protect the European Championship soccer tournament taking place across France for a month.
Islamic State's Amaq news agency released a video Tuesday showing suspect Larossi Abballa, which appears to be filmed inside the home of the victims as security forces closed in.
"I just killed a police officer and his wife," he says, adding: "The police are currently surrounding me."
The video was edited, and the victims do not appear. Neither does the police couple's 3-year-old son, who survived the attack Monday night in the suburb of Magnanville, about 35 miles (55 kilometers) west of Paris.
Paris Prosecutor Francois Molins said Abballa posted the video on Facebook, and that he made the declaration of allegiance to IS in response to the group's calls to "kill non-believers where they live," and with their families.
Amaq reported that an IS fighter carried out the attack, and prosecutor's office spokeswoman Agnes Thibault-Lecuivre said French authorities have "no reason" to doubt the claim.
Abballa stabbed Jean-Baptiste Salvaing, 42, a police commander in the Paris suburb of Les Mureaux, outside his home late Monday, Molins said. Abballa then went inside and took Salvaing's partner and 3-year-old son hostage. He killed the woman, who was a police administrator in the suburb of Mantes-la-Jolie, but did not harm the boy, Molins said.
Aballa was killed by police after a three-hour standoff.
Molins said three people — aged 27, 29 and 44 — were detained Tuesday in the investigation. He did not provide any other details.
French President Francois Hollande said after an emergency security meeting Tuesday that it was "incontestably a terrorist act" and that France faces a threat "of a very large scale."
"France is not the only country concerned (by the terrorist threat), as we have seen, again, in the United States, in Orlando," he said.
Hollande later said he wants additional security efforts to be deployed and vigilance to be increased to "its highest level." He didn't provide details.
Abballa, 25, was from Mantes-la-Jolie and was sentenced in 2013 to three years in prison for recruiting fighters for jihad in Pakistan, according to two police officials. The officials spoke on condition of anonymity because they were not authorized to be publicly named discussing investigations.
A resident of the apartment building where Abballa lived, who did not want to give his name, said police raided it early Tuesday.
Neighborhood resident Henriette Yenge, who lives and works near the building, said she would say hello to Abballa when he went to the mosque around the corner.
"He was a neighborhood kid," she said. "I was surprised it was him. It's sad to see things like that."
Hours before the killing, Abballa went to his neighborhood mosque and prayed so long that mosque employees had to make him leave. Rector Mohamed Droussi said Abballa was reading the Quran for a long time, and was the last one to leave.
"I took the key and I said, 'we are closing,'" Droussi said.
He said he is concerned about radicalization, and the mosque often addresses the issue, to "ask the youth to stay on the right path."
A Facebook profile bearing the name Larossi Abballa — which vanished from the internet early Tuesday — showed a photo of a smiling, bearded man. Two recent posts featured videos critical of Israel and Saudi Arabia. The last publicly available post was a mock-up of the European Championship logo, highlighting what the poster said were masonic and occult symbols.
"Some will say we see evil everywhere!" Abballa said in a message posted about 18 hours before the attack.
On Tuesday, Interior Minister Bernard Cazeneuve visited the police station in Les Mureaux where Salvaing worked. He said more than 100 people seen as potential threats have been arrested in France this year, including in recent weeks.
France, like other countries in Europe, has seen a series of stabbings aimed at police officers or soldiers and carried out by Muslim radicals.
Monday's attack shook police officers, and Cazeneuve said they would be allowed to take home their service weapons.
"Today every police officer is a target," Yves Lefebvre of police union Unite SGP Police-FO told The Associated Press. He said attackers are "professionalizing" and can now find police in their homes.
In Paris, the Eiffel Tower was lit up Monday night in the colors of a rainbow to honor victims of Saturday's mass shooting at a gay nightclub in Orlando, Florida, that killed at least 49 people. The gunman declared his allegiance to IS in phone calls to police, but his motives remain unclear.