Maya Vidon

Special for USA TODAY

PARIS — The suspect in the killings of a police commander and his partner in a Paris suburb pledged allegiance to the Islamic State and had a list of other targets, the Paris prosecutor said.

François Molins told a news conference Tuesday that suspect Larossi Abballa, later killed by police, was responding to a statement by the militant group calling on followers to attack "non-believers" in their homes.

His targets included rappers, journalists, police officers and public officials, Molins said.

Molins said suspect Abballa stabbed Jean-Baptiste Salvaing, 42, a police commander in the Paris suburb of Les Mureaux, to death outside his home in Magnanville, about 35 miles northwest of central Paris on Monday evening. Salvaing was dressed in plain clothes.

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Abballa, 25, entered the house and held the commander’s partner and their 3-year-old son hostage before killing the woman, who Molins said was a police administrator in the suburb of Mantes-la-Jolie.

Police stormed the house and killed the attacker and the woman was found dead. Molins said the young boy was found safe and well but was "very shocked" and was taken to hospital.

President François Hollande said Tuesday the killings were “incontestably a terrorist act." He said that France was facing a terror threat “of a very large scale."

“France is not the only country concerned, as we have seen, again, in the United States, in Orlando,” Hollande said.

Molins said the attacker posted a 12-minute video claiming responsibility for the killings on Facebook.

Abballa filmed himself shortly after the killings as police surrounded the home. He read in both French and Arabic from a notebook, addressing the Muslim community, "What has happened to you, how did you get there? What punishment has fallen onto you? You govern the world and find yourself governed. We are in an era where prophet killers are wishing us happy Ramadan, what humiliation!"

Abballa also had a message for his "brothers" imprisoned in French jails, "Know that Allah has sheltered you, he has set you aside to keep you by his side, so be patient, be firm with your religion." He called on them to "attack prison guards" even if they bear a Muslim name.

Abballa warned the French authorities: "We reserve you more surprises, for the Euro 2016 ... We to Hollande, we will be merciless and I was merciless with that policeman and his wife." In addressing his family, he said, "I will stop your hearts but you must know that it is for a noble mission. You never wanted to understand my way, thinking I was insane but so is the prophet."

Before Abballa signed offline, he said, "At the moment, the police is surrounding me, I hold a few surprises for them."

Three knives were seized, including one covered in blood, and a Quran was found in a car near the scene, Molins said.

An elite police unit negotiated with the attacker who said he was a soldier for the Islamic State, French officials confirmed.

Molins said three people aged 27, 29 and 44 were detained Tuesday in connection with the investigation.

Mohamed Droussim the rector of Abballa's neighborhood mosque, said he showed up to pray a few hours before the killings after rarely attending services in the last few months and only left when he was told the mosque was closing, the AP reported.

Abballa was previously convicted of terrorism for recruiting fighters for jihad in Pakistan, according to multiple media outlets.

The Islamic State’s Amaq news agency said an Islamic State fighter carried out the attack, citing an unnamed source.

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"We are stunned, shocked, devastated," said Loic Fanouillere, administrative chief of the Alliance Police Union, the largest police union in France.

"A policeman is prepared for the ultimate risk — it is the type of job where you are not 100% sure you will come home in the evening ... but now when your own family is hurt? "An attack on the policeman's family, because he is a policeman, ... this is something we never imagined could happen," he said.

"These people (the Islamic State) are very organized," Fanouillere added. "There are no lone wolves — they are anything but idiots, they know what they are doing very well and all their actions are carefully prepared and ... unfortunately for us today, unstoppable."

Claudio Biondi,a Briton and the head of Canon's photo technical team at the Euro 2016 soccer tournament that is currently taking place in France, said he initially thought it was a local crime after seeing a news report.

"They said it was a husband and wife but it didn't register that it was a terrorist attack — it's not the sort of thing they have done in the past — it is quiet isolated and random," he said.

Terrorists have targeted police in France before.

Two police officers were killed in the attacks in Paris in January 2015 that started with an assault on the offices of the satirical magazine Charlie Hebdo. On the one-year anniversary of those attacks, a man with a knife tried to enter a police station in Paris wearing a fake suicide vest before being killed by police.

Monday's incident is the first terror attack in France since a state of emergency was implemented following November's massacre in Paris that killed 130 people. It occurred during heightened security measures for Euro 2016. Cazeneuve said more than 100 people who were potentially a threat to the nation have been arrested in recent weeks.

Police officials had already expressed concern in the weeks leading up to the Euro 2016 over potential attacks.

Yves Lefebvre, the leader of a local police union in Paris, said the biggest threat during the tournament was "unfortunately the terrorist attacks."

Olivier Duran, a spokesman for the National Union of Security Companies which represents private security firms, said that authorities chose to concentrate "huge security measures" on the open-access fan zones during the tournament. "But terrorism strikes out blindly and sometimes cleverly and looks for alternative targets to those high-security locations," he said.

The terror attack follows a shooting in Orlando early Sunday that killed 49 people. U.S. authorities said the gunman, Omar Mateen, claimed his attack was in support of ISIL but also expressed support for al-Nusra and other rogue organizations that are enemies of the militant group.

Contributing: Jane Onyanga-Omara in London