CHARLESTON, S.C. (AP) — Flooding from days of record-setting rain along the heavily populated East Coast washed out bridges and homes and forecasters warned wind gusts topping 35 mph could down trees and power lines across the Carolinas and Virginia in coming hours. President Barack Obama declared a state of emergency in South Carolina and ordered federal aid to bolster state and local efforts as flood warnings remained in effect for many parts of the East Coast through Sunday. The steady downpour drew its moisture from a slow-moving low-pressure system over the Southeast that has linked up to a finger of tropical moisture from Hurricane Joaquin. The low-pressure system also was expected to whip up stiff northeasterly winds in the Blue Ridge mountains of the Carolinas and western Virginia with gusts up to 35 mph through Sunday, the weather service said. Downtown Charleston was closed off to incoming traffic Saturday as rain flooded roads and left some motorists stranded as flood waters engulfed their cars, including a white BMW with water to the engine. In Ocean City, Maryland, spokeswoman Jessica Waters said moderate high tide flooding Saturday forced street closures in low-lying areas but caused no major damages or injuries.