(Portland, OR) -- An outbreak of Legionnaires Disease has killed one person and hospitalized four others from a Portland apartment building. Residents of the Rosemont Court Apartments are being urged to temporarily move to other housing. Multnomah County is helping residents who don't have a place to go. Legionnaires Disease is a bacteria that exists naturally in water, but can grow in closed systems like plumbing or air conditioning. The building's plumbing system will be drained and cleaned to eliminate the bacteria.