GREAT FALLS - An old cotton mill continued to burn Thursday, keeping about 500 residents out of their homes in this Chester County town south of Charlotte.

The blaze at the former JP Stevens No. 3 mill started Tuesday morning, and firefighters decided to let it burn itself out.

Gov. Mark Sanford visited the site Thursday and declared a state of emergency, which will allow local governments to recoup money spent fighting the fire.

Great Falls Fire Chief John Jones said residents of four streets around the mill - about a quarter of the town's population - were evacuated because of the thick black smoke. The cause of the blaze was not known.

Eddie Murphy, director of Chester County Emergency Management, said the evacuation could last up to a week as the fire continues to burn.

'This is the product of a changing textile industry, the condition of the old mill and things like oils from the old machines,' Murphy said.