HATTIESBURG, Miss. — As the Leaf River rose north of Hattiesburg, Mississippi, 26-year-old Rebecca Bruce and her fiancé grabbed what they could and left the shed where they live. The water was more than 2 feet deep indoors when they left, she said. “We lost everything,” Bruce said Saturday. “I’ve got a book bag full of dirty clothes, and I was lucky to get that.” Bruce was among about 20 people in a Red Cross shelter in the Forrest County Community Center on Saturday, as creeks and rivers continued to rise after torrential rains pounded the Deep South. Downpours — part of a system affecting Louisiana, Mississippi, Arkansas, Tennessee and Alabama — submerged roads and cars, washed out bridges and forced residents to flee homes. At least three people have died in Louisiana alone.