At least two people died, one hit by a lightning and another by a falling tree, as a powerful storm ripped through eastern US on Monday.

Thousands of flights were cancelled, nearly a million homes and businesses – from New York to Alabama – lost power.

Over 50 million people were under tornado and thunderstorm watches.

Power had still not been restored for almost 250,000 homes in the region and over 1,000 flights were delayed.

Evan Christopher Kinley, a 15-year-old boy, was killed by a tree as he exited his car when he arrived at his grandparents’ home during the storm in Anderson, South Carolina, the city’s Fire Department Chief told the BBC’s US partner CBS News.

In Florence, Alabama, police said a 28-year-old man was struck and killed by lightning in a parking lot, according to local media.

The National Weather Service says being killed by lightning is rare – only about 20 people on average are killed by lightning strikes annually.

The storm downed trees and power lines up and down the eastern seaboard.

One tornado was confirmed in McGraw, NY, which is about 30 miles south of Syracuse, NY.

As of Tuesday morning, power still has not been restored for 100,000 people in North Carolina, 95,000 in Pennsylvania and 64,000 people in Maryland.

The Federal Aviation Administration (FAA) issued several ground stops on Monday for airports in New York, Philadelphia, Atlanta and Washington, DC.

Nearly 3,000 flights were cancelled on Monday and almost 7,900 flights were delayed, according to FlightAware.

In the Washington, DC metro area, some federal workers from the White House and Pentagon, were sent home early in anticipation of the late afternoon and early evening storm.

“This does look to be one of the most impactful severe weather events across the mid-Atlantic that we have had in some time,” said National Weather Service meteorologist Chris Strong in a Facebook live briefing.

About 30 miles north of Baltimore, in Westminster, Maryland, 33 adults and 14 children were trapped in their cars for several hours after strong winds knocked down more than 30 utility poles, CBS News reported.

The National Weather Service issued a Level 4 out of 5 risk for the first time in decades for the area.

There were wind gusts up to 60mph in the region and emergency crews had to rescue dozens from flash flooding.