A powerful storm ripped through a family campground, trapping campers under downed trees and injuring at least nine people.

Police said the narrow, localized thunderstorm cell caused extensive damage at the park. "It was pretty fierce here," Fire Chief Jay Lord said.

He said it took about an hour to free one camper after a tree landed on his trailer.

"People were just screaming," said Rebecca Duclos, a Manchester (search) woman who was staying with her husband and two children at the Wakeda Campground (search) on Route 88.

Duclos said it was "pitch black" after the storm had passed late Friday. Power lines and trees were downed at the campground and along the roads leading to it.

Josh Grant, of Newbury, Vt., said his parents were hospitalized after a tree crushed their camper. He said both were conscious when reached by rescuers, but were pinned and impaled by branches.

According to its Web site, the Wakeda Campground has 400 camp sites and cabins over 180 acres, not far from New Hampshire's seacoast.

The Red Cross also opened a shelter at the Lincoln-Ackerman School (search) for people whose campsites were seriously damaged.