It was shortly after 5 p.m. when warnings went out over a public address system and social media for people at Pocono Raceway to take cover. That's when eight people were struck by lightning in the grandstand parking lot and two others were struck in a camping area. One of the victims was 41-year-old Brian Zimmerman, who died at the scene. Another person was listed in critical condition.
Officials say they are unsure if there were multiple strikes or if all 10 people were hit by a single bolt of lightning. A severe storm warning had been issued at the track about 45 minutes before, and it has left some wondering why the race wasn't called earlier.
The storm was part of a line of severe overnight weather that caused flash flooding from New Hampshire to Pennsylvania. Severe winds, hail and hundreds of lightning strikes plagued states along the east coast, including a strike at a children's baseball facility in New Hampshire.
In Pittsburg, over an inch of rain fell in a matter of minutes, nearly washing away a woman in her truck.
In New Jersey, severe winds knocked over trees and tents, while lightning strikes took down power lines and left about half the town of Edgewater without power.
ABC News and the Associated Press contributed to this report.