A few customers in Waynesboro, Pa., also lost power, Fletcher said.
Franklin County Emergency Services was busy with storm-related calls, but none major, a dispatcher said.
In Washington County more than 1,000 customers lost power during the storm, with most of those just outside Hancock, Fletcher said. Several crews were working in that area, with power expected to be restored by midnight or early morning.
Those power outages were caused by typical storm damage - winds and trees knocking down wires, Fletcher said.
Random houses on West Side Avenue, Bryan Place and Avon Road in Hagerstown's West End lost power for about an hour Friday night, said Tracey Matzen, a clerk operator with Hagerstown Light Department.
Matzen said crews also responded to a wire knocked down in an alley behind Kuhn Avenue around 6:40 p.m.
Other than the power outages it was pretty quiet in Washington County, said Emergency Specialist Jim Blevins with Washington County Emergency Services. Blevins said he was amazed there wasn't more damage in the county.
"We watched on the radar. We thought we were going to get nailed," Blevins said.
Frequent lightning, heavy rains and winds up to 32 mph whipped through Hagerstown during the thunderstorm, according to local weather observer Greg Keefer's Web site at www.i4weather.net.
The storm left about an inch of rain, according to Keefer's Web site.
In Frederick County three houses were struck by lightning, with one catching fire shortly before 7:30, according to Frederick County Emergency Services and the New Market Fire Co. No further information was available.
Lightning strikes caused minor damage to another house in New Market and one in Monrovia, a 911 dispatcher said.
Severe thunderstorm warnings had been issued for Washington County, Berkeley County, W.Va., and Franklin County, Pa., said National Weather Service Meteorologist Andy Woodcock.
A line of thunderstorms developed over the Blue Ridge Mountains Friday afternoon, moving east and hitting the Tri-State area around dinner time, Woodcock said.
There was a 30 percent chance of thunderstorms today, he said.