Two military grenades and “unidentified chemicals” have been found at a property in Lowestoft, leading to 60 houses being evacuated.
Officers have set up a 100m cordon at Normanshurt Close while they wait for an Army bomb disposal team to arrive.
Suffolk Police made the discovery while executing a warrant just before 13:00 BST. They are being supported by Suffolk Fire and Rescue crews.
A man in his 50s has been arrested on suspicion of possession of a firearm.