Kenyan police say they have conducted dawn raids on two mosques in the coastal city of Mombasa, recovering grenades and ammunition.
One person was shot dead by police and more than 250 people were arrested during the operation.
Police said the Masjid Musa and Shakinah mosques were being used to store weapons.
They have accused the Masjid Musa mosque of having ties to the Islamist militant group al-Shabab.
Al-Shabab, which is based in neighbouring Somalia, has carried out several attacks in Kenya since 2011, when Kenya sent troops into Somalia to battle it.
Police say they recovered a pistol, eight grenades and a flag associated with al-Shabab at the mosques.
One man was shot dead during the raid after he “attempted to hurl” a hand grenade at police officers, Mombasa police chief Geoffrey Mayek told reporters.