An explosion wounded six people in the Afghan capital and revealed what international peacekeepers described Sunday as a clandestine bomb factory.

Police who joined NATO (search) troops in investigating the blast, which happened Saturday in a residential compound in west Kabul, arrested three men, peacekeepers' spokesman Cdr. Chris Henderson said.

A police official identified one of the men as Mohammed Hakim, the owner of the house. But it was not clear the men had links to any militant groups.

"It is believed that the explosion occurred as the three men were assembling bombs," Henderson said. "Their intended actions could easily have killed many innocent people."

The family living at the compound said they thought the explosives were for quarrying, district police chief Mohammed Alam Siasi (search) said.

The blast injured three children, two women and one man, Henderson said. Their condition was not known.

Canadian troops found electrical switches, 44 pounds of explosives and 550 pounds of ammonium nitrate, a farm fertilizer which can be used to make explosives.

Siasi, chief of police in Kabul's District Five, said authorities were searching for a man identified only as Fazel from east Kabul (search), who allegedly supplied the fertilizer and paid the family to grind it up.

Fazel told the family he needed explosives to break up rocks for use in construction, Siasi said.

Kabul has seen many bomb and rocket attacks over the past year.

Most have caused no injuries and little damage, although three soldiers from the NATO-led international peacekeeping force that patrols the capital have died this year in two suicide bombings and a grenade attack.