Sanford asked the hundreds of evacuees to be patient as emergency crews fight the fire and police enforce the mandatory evacuation.

The governor came to the southeastern Chester County river town of about 2,200 residents to see first-hand the effects of the mass evacuation and smoky ruins at the J.P. Stevens Mill No. 3 that caught fire early Tuesday. The cause of the fire has not been determined.

"After three days of what we observed, we needed to take a new approach," Eddie Murphy, director of Chester County Emergency Management, said about the request for state aid.

The state of emergency declaration gives local governments in Great Falls and Chester County a chance to recoup the costs of fighting the fire and paying for extra law enforcement and equipment, Sanford said.

Sanford said he understands the frustration people have in not being able to go home, but toxicity in the air demands forced displacement until the danger is over.

"The state will be as helpful as we can," Sanford said.

The governor praised both the local response in the first three days and defended the state's response. Emergency plans require local departments and governments to deplete resources before asking for state help -- and then potentially federal government help -- if needed, Sanford said.

"The bottom line is the locals have handled it very well," he said.

Neither Sanford nor Murphy had an estimated cost of the fire so far.

The smoke plume from the fire has hydrochloric acid levels lower than those that typically cause respiratory, sinus or eye irritation, said Clair Boatwright, spokeswoman for the S.C. Department of Health and Environmental Control.

However, the best protection is distance from the fire, she said.

Local hospitals have reported no patients with respiratory ailments from the fire, she said. One doctor reported to DHEC a patient with a potential respiratory problem, and five calls were made to area DHEC offices about potential ailments, she said.

Social workers also were on hand to handle stress and discomfort from displacement, she said.

Runoff water from fighting the fire lowered acidity levels in a small section of the Catawba River near the mill to below-normal levels. But drinking water has not been affected, Boatwright said.

A privately owned catfish pond was a concern for DHEC on Thursday, Boatwright said. The pond was being watched closely to observe if fish died there. But early reports showed no fish kills, she said.

The state of emergency declaration is the first in the state since a toxic train derailment in Graniteville in January 2005. The declaration means small businesses may be eligible for low-interest loans, said John Paolucci, operations director for the S.C. Emergency Management Division.

Before the state of emergency was declared, officials brought in two heavy equipment machines to give firefighters access to the smoldering building. But the machines were ineffective, Murphy said, and the fire continues to burn.

The mill, built around 1930, has concrete walls, Murphy said. Some of the walls have collapsed and have embers burning beneath. Shifting winds, a factor in the evacuations, have blown dangerous smoke from the mill fire in most every direction, Murphy said.

The York/Chester County chapter of the American Red Cross set up an emergency shelter at Great Falls High School on Tuesday. The shelter will remain open for as long as residents have a need, said executive director Rebecca Melton.