State Police spokeswoman Corrine Geller said a search continued at the Cherrystone Family Camping Resort on Chesapeake Bay for any additional casualties.
Riverside Shore Memorial Hospital was treating 25 people injured by the storm, with three in critical condition, according to spokesman Peter Glagola.
Most of the injuries involved broken bones and head trauma, Glagola said, adding that the hospital didn't expect additional patients.
Geller said others staying at the campground in Northampton County were transported by bus to a local school set up as a temporary shelter.
The National Weather Service said a cluster of "supercells" ahead of a cold front formed a storm over Chesapeake Bay just after 8 a.m. ET.
According to the weather service, the storm intensified as it moved on ashore about 30 minutes later. The area was under a tornado warning issued at 8:20 a.m.
Photos from the scene showed overturned campers, with a downed tree crushing one vehicle.
The campground that opened in 1964 occupies 300 acres with 725 sites including cabins, cottages, and deluxe campers, its website says.
By Marlena Baldacci
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