Heavy rain and lightning early Wednesday morning forced dozens of Girl Scouts who were camping on the South Lawn of the White House to take shelter inside the Eisenhower Executive Office Building.

First Lady Michelle Obama hosted the scouts for an historic camp-out to promote her "Let's Move" campaign designed to get young people exercising more outdoors.

Early in the evening, the first lady told the girls that they were making history with their South Lawn sleepover — that no one had ever camped out in tents on the White House grounds before. The president also made an appearance and spoke to the young scouts.

"What are you guys doing in my yard," he jokingly asked the campers. "When did you guys show up?"

But a violent storm swept through the region with heavy winds, rain, lightning and thunder, which prevented the troop from finishing the night outside. White House officials were forced to move the fourth-graders and their chaperones into the office building, which is right next to the White House.

An administration official said they were brought up to the fourth floor of the Eisenhower Executive Office Building ahead of the storm, where they remained until morning.

"All safe and sound!" the official remarked.