Four men and two women are being questioned by the police about the discovery of three firebombs at a house in Ballymena, Co Antrim.
The devices were made safe by British Army bomb experts after they were found at Fisherwick Gardens in Ballymena.
The PSNI has asked business owners in Coleraine, Strabane, Derry and Ballymena to thoroughly check their premises .
A wave of fire bombings has destroyed several businesses across the North.