An 84-year-old priest has been killed with a knife, and another person seriously wounded, after two men with alleged links to the Islamic State of Iraq and the Levant (ISIL) took several people hostage in an attack on a church in northern France.

Father Jacques Hamel reportedly had his throat slit on Tuesday before French police entered and shot dead the attackers, a French police source told the Reuters news agency.

The Paris-based AFP news agency, citing the ministry, said a second hostage was "fighting for life" after the incident in Saint-Etienne-du-Rouvray, Normandy, but indicated that the other three hostages had made it out unharmed.

Later on Tuesday, French prosecutor Francois Molins identified one of the attackers as 19-year-old Adel Kermiche, who was reportedly under surveillance after having tried to travel to Syria twice.

He was under house arrest and wearing an electronic monitoring bracelet at the time of the attack.

Speaking outside the church, French President Francois Hollande called it a "dreadful terrorist attack" and told reporters the assailants had pledged allegiance to ISIL, also known as ISIS.

The ISIL-linked Amaq website said two of its "soldiers" had carried out the attack.

"We are put to the test yet again," Hollande said. "The threat remains very high."

In a separate televised national address on Tuesday evening, Hollande declared "our country is at war...this war will be long".  


READ MORE: Is Europe under attack?


Al Jazeera's Natacha Butler, reporting from Paris, said the two assailants entered the church during a morning service.

"There were worshippers there; there were nuns; and they took those people hostage, including that priest who was killed. One of the nuns managed to escape, French radio reported, and it was that person who raised the alarm and called the police," Butler said.

French police arrested one person in connection with the attack on Hamel and four other hostages [Reuters]

"Special forces arrived shortly after and the hostage-takers were then killed when they tried to leave the church."

The Paris prosecutor's office said the case had been handed to "anti-terrorism" judges for investigation. 

French police arrested one person in connection with the attack, a source close to the inquiry told Reuters on Tuesday afternoon.

The Vatican in a statement called the incident a "barbarous killing", saying it was even more heinous because it happened in a sacred place. 

String of attacks

The attack comes as France is on high alert after an attack in Nice that killed 84 people and a string of deadly attacks last year claimed by ISIL.

The country is in a state of emergency and boosted visible police presence in the wake of the attack in Nice this month.

The security measures have been extended four times since assailants, who pledged allegiance to ISIL, struck Paris in November, killing 130 people at restaurants, a concert hall and the national stadium.

The Nice massacre has triggered a bitter political spat over alleged security failings, with the government accused of not doing enough to protect the population.

French police have detained one man in connection to the attack at the church in Saint-Etienne-du-Rouvra in Normandy, France [Reuters]

READ MORE: The future of Europe after the Brussels attacks


Prime Minister Manuel Valls had warned earlier in the week that the country would face more attacks as it struggles to handle fighters returning from wars in the Middle East.

France has been concerned about the threat against churches ever since a foiled plot against one in the Paris suburb of Villejuif in April last year.

Sid Ahmed Ghlam, a 24-year-old Algerian IT student, was arrested in Paris on suspicion of killing a woman who was found shot dead in the passenger seat of her car, and of planning an attack on a church.

Prosecutors said they found documents about al-Qaeda and ISIL at his home, and that he had been in touch with suspected fighters in Syria about the plan to attack a church.

Source: Al Jazeera and agencies