French President Francois Hollande (R) and Interior Minister Bernard Cazeneuve (L) leave the city hall after two assailants had taken five people hostage in the church at Saint-Etienne-du -Rouvray near Rouen in Normandy, France, July 26, 2016. [Photo/Agencies]

PARIS -- French President Francois Hollande on Tuesday reiterates calls for the nation's unity to win a long battle against terrorism in a brief televised address after two men claiming allegiance to the Islamic State (IS) slaughtered a priest in northern France.

Earlier Tuesday, two armed men with knives entered a church in Saint-Etienne-du-Rouvray, north France during a morning mass and seized five people including the priest. The priest was killed by the two hostages takers who were later shot dead by police units. A second victim was in critical situation.

The Islamist militant threat to France and Europe has never been so severe as now, he said, pointing that the war against terrorism both abroad and at home will be long. "It is our unity that will make us strong. We need to form a bloc to win this war... but I assure you, we will win this war."

Denouncing "an unforgivable act," he insisted that the government will be determined to apply the anti-terrorist laws while respecting rights and freedoms.