PARIS » French Interior Minister Bernard Cazeneuve has denounced what he called “an abject terrorist act” after an attacker killed two police officials outside Paris, and warned that France, Europe and the West remain under a high threat of the kind of extremist violence that hit an Orlando night club.

Speaking after an emergency meeting convened Tuesday morning by French President Francois Hollande, Cazeneuve said more than 100 people seen as potential threats have been arrested in France this year, including in recent weeks.

France has been on particularly high alert as it hosts Europe’s top sporting event, the monthlong European Championship soccer tournament, and is still under a state of emergency after deadly Islamic State attacks in November.

The threat “is high in France, it’s high in Europe, it’s high in the Western world as shown by the events that happened 48 hours ago in the United States,” Cazeneuve said.

He did not give details about Monday’s attack in the Paris suburb of Magnanville, in which a knife-wielding attacker stabbed killed an off-duty senior police officer and his partner, a woman police official. The couple’s 3-year-old son was unharmed, and the attacker was killed in a police raid.

French anti-terrorism prosecutors are investigating. The Islamic State’s Amaq news agency cited an unnamed source as saying an IS fighter carried out the attack, but the extremist jihadist group has not officially claimed responsibility.

The police commander was attacked outside his home, about 35 miles (55 kilometers) west of Paris, then retreated indoors and elite police commandos laid siege to the residence, eventually storming it after a roughly three-hour standoff.

France, like other countries in Europe, has seen a series of stabbings aimed at police officers or soldiers and carried out by Muslim radicals. IS has encouraged its supporters to stage such attacks.

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.