28-year-old killed by lightning, teen fatally hit by tree amid severe storms

At least two people have been killed by the severe weather that slammed the East Coast overnight.

A 28-year-old man died after he was struck by lightning in Florence, Alabama, and a 15-year-old boy died after being hit by a falling tree outside his grandparents' home in Anderson, South Carolina, according to local authorities.

The storms brought torrential rain, destructive winds, massive hail and loud thunder to the eastern part of the country on Monday afternoon and evening.

Straight-line winds gusted to 71 miles per hour in Georgia and 63 mph in Maryland, where power lines and trees came crashing down. Grapefruit-sized hail was reported in Virginia.

In Washington, D.C., federal employees, including at the White House and the Pentagon, were instructed to leave work early Monday afternoon due to the weather.

In Westminster, Maryland, downed electric poles trapped 33 adults, 14 children and a dog inside cars on a major highway. It took several hours for them to be rescued, but there were no reported injuries, according to state authorities.

"This is devastating," Maryland Gov. Wes Moore told ABC News. "This is not going to be hours -- this is going to be days to making sure that we can get everyone back up when it comes to power and be able to restore, restore what's happening on the roads."

More than 10,000 flights were canceled or delayed across the country on Monday, impacting airports in cities including Atlanta, New York, Baltimore and Washington, D.C.

The storms knocked out power to 1 million customers Monday night. More than 295,000 customers remained without power Tuesday morning across Pennsylvania, North Carolina, Maryland, Tennessee and Georgia.

Most of the severe weather has since ended for the East Coast, but a lingering storm system in New England could bring isolated severe thunderstorms with gusty winds and even an isolated tornado. Much of New England also remains under a flood watch until Tuesday evening as heavy rainfall could trigger flash flooding.

The main threat of severe weather shifts to the Great Plains on Tuesday, particularly Colorado, Nebraska and Kansas, where an isolated tornado and huge hail is possible.

Other areas under threat on Tuesday will be from Mississippi to Georgia, where damaging winds will be possible.

The stormy weather will continue into Wednesday and over the weekend with plenty of rain in the forecast. Areas from the Midwest to the Deep South could see localized flooding.

ABC News' Matt Foster and Lauren Minore contributed to this report.

Disclaimer: The copyright of this article belongs to the original author. Reposting this article is solely for the purpose of information dissemination and does not constitute any investment advice. If there is any infringement, please contact us immediately. We will make corrections or deletions as necessary. Thank you.