Dutch police have arrested eight suspected Muslim radicals as part of the investigation into the killing of an outspoken filmmaker, prosecutors said Wednesday.

The suspects were detained in the 24 hours after Theo van Gogh was killed as he bicycled down an Amsterdam street, according to the spokeswoman for the prosecution, Dop Kruimel. Six of the detainees are Moroccan, one is Algerian and the other has dual Spanish-Moroccan nationality, she said.

The suspected killer -- a 26-year-old Muslim with dual Moroccan-Dutch citizenship -- was arrested Tuesday after a shootout with police. He has not been identified.

Van Gogh, 47, a great grandnephew of the painter Vincent van Gogh, had received death threats after his recent film sharply criticized how women are treated under Islam. He was repeatedly shot and stabbed. "Don't do it. Don't do it. Have mercy. Have mercy!" the Algemeen Dagblad newspaper quoted Van Gogh as begging his killer.

Another Dutch newspaper, De Telegraaf, said the killer shot Van Gogh eight or nine times, then calmly slipped the weapon into the pocket of his beige raincoat before bending over Van Gogh and slitting his throat.

Piet Hein Donner, the Dutch justice minister, said the suspect "acted out of radical Islamic fundamentalist convictions" and said that he had contacts with a group that was under surveillance by the Dutch secret service.

The suspect is allegedly a friend of Samir Azzouz, an 18-year-old Muslim of Moroccan origin awaiting trial on charges of planning a terrorist attack against a nuclear reactor and Amsterdam's Schiphol Airport, NOS Dutch national television reported. Azzouz was part of a group arrested in October 2003 but released for lack of evidence. He was re-arrested in June.

Van Gogh, an award-winning filmmaker, television producer and newspaper columnist, once mocked a prominent Dutch Jew, referred to Jesus as "the rotten fish" of Nazareth and called a radical Muslim politician "Allah's pimp."

In August, he released the fictional film "Submission," about a Muslim woman who is beaten and sexually abused, drawing the ire of some Muslims and generating death threats against him.

About 20,000 people poured into Amsterdam's central square to protest the attack. Many blew horns and whistles and banged pots and pans. The government held late-night crisis meetings and the immigration minister met with Muslim groups to discuss how to avoid violent confrontations with the Muslim community.

Dutch Muslim groups condemned the killing and called for reconciliation, expressing fears of reprisals against Muslims. Several Muslim groups planned rallies in the Dutch capital to protest the attack.

Mourners pause outside the house of Theo van Gogh, who was shot and stabbed to death in Amsterdam.