WAVELAND (AP) — Mandatory evacuation had been ordered by Tuesday in low-lying areas of all three Mississippi coastal counties, and waves were washing across beachside roads as Hurricane Isaac swirled offshore.

All three coastal counties also set overnight curfews.

An evacuation order came Tuesday in Harrison County, which is in the center and has the largest population. The order covers about 30,000 people, or nearly one-sixth of the county’s population. Evacuation orders for low-lying areas came Monday in Hancock County, which borders Louisiana; and Jackson County, which borders Alabama.

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.

The Mississippi Gaming Commission on Tuesday ordered the closing of all coast casinos, which are on or near the water.

“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.

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 has no plans to evacuate.

“We’re going to stay and ride it out. I raise pigs and a few cows. I’m going to stay and make sure they’re OK,” he said.

Meanwhile, people who don’t have cars or can’t drive were being transported to shelters. Lacy said nearly 600 people requested rides, though some later made other arrangements. Lacy said four shelters opened in Harrison County at 8 a.m., including one for pets.

As Isaac pushed closer to shore, bands of rain began to pelt the Mississippi coast, but at times gave way to sunshine. Many beachfront businesses were closed. Harbors were mostly empty, other than disabled boats that couldn’t be moved. In Pass Christian, a sail boat had washed aground near the beach and bobbled in the surf. Many houses were boarded up.

Water was creeping into a parking lot that faces Biloxi Bay and some was washing into the parking garage of the Palace Casino in Biloxi.

Long Beach residents Charlotte Timmons and Brenda Batey took a sunrise beach walk before heading home when rain began. The women said they have prepared their homes and won’t take risks, but they think Mississippi will be spared the devastation of some past storms.

Both women lost their homes to Hurricane Katrina, which destroyed a large chunk of the northern Gulf Coast. If it looks like Isaac will strengthen or take a more direct aim at Mississippi, they will move out of harm’s way.

Since Katrina, people have a more cautious attitude toward tropical weather, perhaps so cautious that there’s a danger of complacency setting in after near misses, Timmons said.

“It’s like crying wolf,” said Timmons, a 63-year-old retired media manager. “If they make such a big deal and start moving people out (too soon) and then it fizzles, people might not leave the next time.”

Timmons and Batey said they have friends who just can’t understand why they moved back to the coast after Katrina. But they can’t imagine not taking morning walks on the beach.

“People say, ‘Why do you still live there?’ You can’t explain it,” said Batey, a 60-year-old retired language teacher.