Gustav howled into Cuba's Isla de Juventud as a monstrous Category 4 hurricane on Saturday while both Cubans and Americans scrambled to flee the path of the fast-growing storm. Forecasters said Gustav was just short of becoming a top-scale Category 5 hurricane as it powered its way toward mainland Cuba, where authorities were hurriedly evacuating more than 240,000 people from the nation's tobacco-rich western tip. The hurricane was projected to plow into the oil-rich Gulf of Mexico at full force Sunday, and reach the US coast Monday afternoon. A hurricane watch was issued from Texas east to Florida, an area that includes New Orleans, which Hurricane Katrina devastated in 2005. More than a million Americans took buses, trains, planes and cars as they streamed out of New Orleans and other coastal cities, where Katrina killed about 1,600 people. Gustav already has killed 81 people by triggering floods and landslides in other Caribbean nations.