WASHINGTON — Thousands of residents in the Mid-Atlantic region were still without power Friday afternoon after a line of destructive storms swept through the area a day earlier.

More than 100,000 residents lost power after thunderstorms battered the region Thursday. Pepco said it had restored power to some 80,000 customers, with many still in the dark in Montgomery County, Md.

At Maryland Gov. Martin O'Malley's urging, the Maryland Public Service Commission intends to investigate why Pepco has had trouble restoring outages more quickly. It took days for Pepco to restore power last week after another storm battered the area.

Pepco spokesman Bob Hainey said the utility company will cooperate with any investigation.

"People are experiencing this back to back," he said. "These are violent storms that rip up the system every time. We have to rebuild the system each and every time."

Pepco expects most residents to have power restored by midnight Friday.

Meteorologists predict scattered showers will continue over the weekend, but the weather will pale in comparison to Thursday's storms, the National Weather Service said.

On Friday morning, 30 traffic signals were still without power in Montgomery County — the hardest hit of the Washington suburbs. Several county parks and roads remained closed because of downed trees and power outages. In Chevy Chase, Md., clean-up crews worked through the day to tackle the worst of the wreckage, including toppled power lines.

"It's like a war zone," said Alice Fernandes, owner of Ed's Tree Service in Beltsville, Md. "We could probably be cleaning up for months. It's a huge area and there's just so much destruction."

Chevy Chase resident Andrew Baines took the day off Friday to break down fallen trees in his yard. He was at work early Thursday morning when an oak fell on his roof during the storm, waking his wife and blocking the front door.

"I called her and she said, 'I don't know what to do. The tree is on the house,'" Baines said. She was able to exit safely through the back door, he said.

In Washington, crews focused on clearing fallen trees one day after the storms.

Fewer than 1,000 Baltimore-area residents lacked power Friday afternoon, down from more than 30,000 at the height of the outages, BGE said.

In northern Virginia, about 300 Dominion Virginia customers had no power Friday afternoon.

No storm-related deaths were reported in the region.

Senior Meteorologist Howard Silverman of the National Weather Service said the record-high temperatures in the Washington area can claim a role in the violent storm season.

"It is typical to have severe summer thunderstorms each year," Silverman said. "Thunderstorms are a way the earth redistributes the heat."