BALTIMORE -- More strong storms moved in on the eastern U.S. on Thursday, even as hundreds of thousands of people remained without power.

The number without power was dropping, but more than 500,000 customers were still using generators, hauling water and camping out almost a week after storms knocked out electricity to millions in the nation's capital and beyond.

At least 27 people have been killed in the storms or their aftermath since Friday, not including deaths from heat-related causes.

Pepco, a public utility covering much of Washington, D.C., and the Maryland suburbs, was facing harsh criticism. As of Thursday morning, the utility said it had restored power to more than 90 per cent of customers.

In the Virginia suburb of Arlington, just outside Washington, the Bolivian-born couple Lidia and Walter Valdez said a week without air conditioning reminded them of trips to the Amazon in their native country.

"We are so desperate!" Lidia Valdez said. "We are taking cold water showers at midnight, in the morning. Three, four times a day."

Meanwhile, a new round of summer storms was making its way across Michigan and Ohio, knocking down trees and power lines. Some new outages came in areas that already had power restored.

Utilities said more than 300,000 homes and businesses across Michigan were without power.

Cooling stations and shelters remained open across West Virginia and in other states.