GULFPORT (AP) — Hurricane Gustav brought down tree limbs and flooded coastal roads as it slapped at Mississippi’s Gulf Coast on Monday.

A hurricane warning covered Mississippi’s three coastal counties, which also braced for possible flash flooding and tornadoes. Traffic on major roads along the coast was limited mostly to emergency vehicles.

The Mississippi Department of Transportation said coastal U.S. 90 was closed due to storm surge flooding and drivers were told to take alternate routes. Waves crashed over a seawall, sending water coursing over two lower lanes of the highway. Street signs flapped in the wind.

Greg Flynn, a Mississippi Emergency Management Agency spokesman on the coast, said very strong winds had knocked out power to 2,200 homes and businesses in Waveland, but ‘‘there’s nobody there.’’

He said most residents of the coastal town, almost wiped away by Katrina and Hurricane Camille in 1969, had fled Sunday to higher ground.

Flynn said that as of Sunday, 11,848 people were living in shelters in Mississippi, including 3,134 in the state’s six southernmost counties.

He said three people were rescued Monday morning from flood waters off of Interstate 10 in Hancock County near the Jordan River. He had no other details. To the north, bands of strong wind and rain had spread north of Hattiesburg by midmorning. In Jackson, there were wind gusts and occasional light drizzle. A tropical storm warning was posted throughout the day Monday for western and central Mississippi and northeast Louisiana.

While Gustav’s fury was focused on the Louisiana coast, Mississippi officials took no chances. As of Sunday evening, there were 200 state law enforcement officers and 1,500 National Guard soldiers on the Mississippi Gulf Coast. Maj. Gen. Bill Freeman, Mississippi’s adjutant general, said 1,200 more soldiers would arrive Monday. For residents along the state’s manmade white sand beaches, memories of Hurricane Katrina three years ago linger like a wound that is painfully slow to heal.