COLUMBIA -- Utility crews are making progress as they work to restore power to South Carolinians who lost service during this week's snow, sleet and freezing rain.

But utility company officials have warned that it could be next week before all power is restored.

The most serious problems have been reported in Aiken and Dorchester counties.

Emergency Preparedness officials said Friday that about 228,000 customers were without service. That's down from a peak of about 346,000 late Thursday, the peak in the storm.

The Highway Patrol says troopers have responded to more than 4,500 calls. That includes more than 1,300 wrecks and more than 1,100 reports of trees on roadways.

Most roads are in good condition, but officials say many secondary roads still have snow, slush or ice.