Zimmerman stood near in his car in the parking lot behind the grandstands when he was struck and was in cardiac arrest when paramedics reached him less than five minutes after the strike. He was dead upon arriving at Pocono Medical Center, according to Monroe County coroner Bob Callen.
Nine other fans were injured and were taken to local hospitals as a result of the storm that caused the race to be halted after 98 laps. The one victim initially listed in critical condition was upgraded to stable condition Monday afternoon.
According to track officials, all 10 spectators were injured in the parking lot after the race. A fan told The Sporting News that he saw a lightning strike near the Turn 3 grandstands.
Zimmerman, from Moosic, Pa., was treated by medical personnel at the track's infield medical center before being transported by ambulance to the hospital.
Pocono track spokesman Bob Pleban said warnings about lightning in the area were issued after the race was stopped. The National Weather Service issued a thunderstorm warning roughly 30 minutes before the race was stopped due to heavy rain.
"The visibility was very poor and all of a sudden (I) saw a bolt of lightning right in front of our windshield," Kyle Manger told the Sporting News. "When it became a little more visible, we saw two bodies next to a destroyed tent with people scrambling."
Track officials had posted warnings the track's Twitter page near the end of the race telling fans to "seek shelter as severe lightning and heavy winds are in our area."
In 1983, two NASCAR fans were killed and six injured in a storm at Dover, Del.