The French president and French police are mourning two police officials killed by an Islamic State militant, as anti-terrorism investigators question three suspects and seek to determine whether the attacker was working with a larger network.

The attack revived French concerns about the IS threat after the group targeted Paris last year.

The Paris suburb of Magnanville is holding a memorial ceremony for Jean-Baptiste Savaing, the 42-year-old police commander who was stabbed outside his house Monday night, and his 36-year-old female companion, a police administrator whose name has not been released.

President Francois Hollande is joining a moment of silence at the Interior Ministry on Wednesday.

Attacker Larossi Abballa, who had a past terrorist conviction, recorded a video during the attack before being killed in a police raid.