Three Dutch policemen were injured by a hand grenade during a terrorism-related raid on a house in The Hague today.
Air space for small planes was closed over the capital during the operation.
Chief Prosecutor Han Moraal said the raid was part of a “continuing investigation into terrorism”, but would not confirm it was related to the killing of filmmaker Theo van Gogh by an alleged terrorist.
Suspects were still inside the building, Hague Police Chief Gerard Bouwman said.
Several streets were cordoned off in a mostly immigrant neighbourhood near the Holland Spoor rail station, and police demanded identification from anyone wishing to leave.
The explosion occurred as police raided the house during an operation. Gunshots were also heard.
Two police officers were admitted to hospital in serious, but not life-threatening, condition, said spokesman Frans van Rijnswou.
A man of Asian descent was seen being dragged from the building clad only in boxer shorts and escorted away.
Van Gogh had received death threats after the release of his most recent film about the treatment of women under Islam.
Six suspects, believed to be members of a terrorist group, are in custody, including the alleged killer, 26-year-old Mohammed Bouyeri, who holds dual Dutch and Moroccan nationality and is suspected of having links to al-Qaida.
There have been more than a dozen arson attacks in the Netherlands against churches and mosques since Van Gogh’s murder in Amsterdam more than a week ago.