Grandillo said he expected power to be restored to most customers in Maryland by noon today and by 6 p.m. in Franklin County.
Hagerstown Fire Department Battalion Chief Richard Hopkins said lightning damaged at least two homes in the city, including one at 1032 Potomac Ave., where lightning melted the structure's electrical system.
"There were several (reports) that were storm-related that dealt with electrical situations in houses," Hopkins said. "There's been a lot of calls."
Hopkins said the department received calls for automatic fire alarms, electrical damage and medical emergencies during the storm.
A spokeswoman for Washington County Emergency Services said a handful of downed-tree reports were referred to the Maryland State Highway Administration.
A spokeswoman there said crews received two reports of trees downed near the Mason-Dixon Dragway.
Carl Babinski, meteorologist with AccuWeather.com in State College, Pa., said the storm came from Michigan, where it caused widespread power outages Sunday evening.
Babinski said Lancaster County, Pa., reported as much as 4 inches of rain. Nearly three-quarters of an inch of rain was recorded at Hagerstown Regional Airport.
Babinski said winds reached as high as 52 mph during the peak of the storm.
In Pennsylvania, a spokesman for Franklin County Emergency Services said trees, poles and wires were knocked down by the storms. No injuries had been reported, the spokesman said.
A National Weather Service spokesman said some barn roofs were lost in Antrim Township and small hail was reported in Quincy, Pa., and Greencastle, Pa.
Grandillo said at 5:30 p.m. that 2,700 customers were without power in Waynesboro, Pa., Fayetteville, Pa., Chambersburg, Pa. and Greencastle. By 10 p.m., about 1,800 customers were still without power, he said.
"We'll be bringing them up throughout the evening," although some will be without electricity into today, he said.
"There was some significant damage in some areas, and new utility poles are needed," he said.
Staff writer Bonnie H. Brechbill contributed to this story.