Isaac could cause flooding far inland in Miss.

They say rain dumped by Isaac could cause significant flooding even hundreds of miles inland in coming days, especially on the state's western side.

"This is a slow-moving system and we expect heavy rain to occur throughout Mississippi," said Federal Emergency Management Agency Administrator Craig Fugate, speaking Tuesday with Bryant at a Mississippi Air National Guard base in Gulfport. "This is not just a storm for coastal Mississippi."

Isaac made landfall at 6:45 p.m. CDT in Plaquemines Parish, La.

Mississippi Emergency Management Agency Director Robert Latham said as many as 175,000 residents of Hancock, Harrison and Jackson counties faced evacuation orders. All three coastal counties set overnight curfews.

The state could see tropical storm-force winds for a long duration, and the broad storm is expected to pump a significant storm tide toward the shore. Water was creeping up on beachside U.S. 90 in Biloxi Tuesday, and storm surge was pushing out of bayous and bays in other neighborhoods, flooding streets.

All along U.S. 90, families stood at the edge of the waves to gawk. The Mississippi Sound, protected by barrier islands, is often as still as a lake. But Isaac began stirring breakers before dawn, as it pumped a storm tide toward the coast. Police struggled to clear piers where water was lapping at the boards, and resorted to bullhorns to tell sightseers to leave the beach

In Hancock County, motorists crept through waves washing across Beach Boulevard in the small town of Waveland. Brandon Ellis, 23, rode a yellow ATV to the beach in Waveland to watch the water roll in.

"It's amazing," he said, pointing to the Gulf of Mexico. "There's usually a walk way right there (behind a sea wall) but it's under water."

Ellis, who was further north in Picayune when Hurricane Katrina hit seven years ago Wednesday, said he had no plans to evacuate.

"I raise pigs and a few cows. I'm going to stay and make sure they're OK," he said.

Harrison County's curfew of 7 p.m. Tuesday to 7 a.m. Wednesday is designed to keep gawkers away from potentially dangerous areas. Gulfport Mayor George Schloegel warned that police would be stern in efforts to prevent looting.

"Don't be out of your homes," he said.

Jackson County set curfews of 10 p.m. Tuesday to 7 a.m. Wednesday and 10 p.m. Wednesday to 7 a.m. Thursday. Hancock County's is 9 p.m. to 6 a.m., beginning Wednesday and extending until further notice.

"This storm is big and it's tightening up and it sat out there for 12 hours south of us and it's pushing that wave action in and there's nowhere for that water to go until it dissipates," said Harrison County Emergency Operations Director Rupert Lacy.