At a demonstration against U.S. participation in the war in Afghanistan, authorities used pepper spray on a group of protesters trying to enter the National Air and Space Museum, forcing the building to close about two hours early. More after the jump…

Wendy L.

(CNN)–One person was arrested, according to Linda St. Thomas, a spokeswoman for the Smithsonian Institution, which runs that and numerous other museums in Washington. She estimated between 100 and 200 people were in the crowd.

Demonstrators railing against U.S. participation in the war in Afghanistan initially gathered Saturday, along with protesters aligned with the national Occupy Wall Street movement, in Washington’s Freedom Plaza. The latter effort started in New York more than three weeks ago, targeting the nation’s financial sector and various social ills, and has since spread to more than a dozen cities.

The Washington demonstrators Saturday chanted “Occupy Wall Street, Occupy H Street, Occupy Everything, and never give it back.” Some moved from Freedom Plaza toward the museum, which is along the National Mall, escorted by District of Columbia police.

Some started to enter the museum to demonstrate against displays of military drones used during the war in Afghanistan. St. Thomas said that one of the protesters pushed a museum security guard against a wall, prompting another guard to respond with pepper spray to force demonstrators outside.

“We wanted to go inside and protest at those particular items of destruction, and the crowd was pepper sprayed going in and was forced out of the building,” said Brian Morrison, one of the protesters.

Araz Alali, a spokesman with the D.C. Police, said his department had no knowledge the museum security was going to pepper spray the protesters.

Demonstrator Greg Slater carried a sign that read “Occupy Wall Street, not Afghanistan.” He said that the protest did not warrant the type of reaction it got from the museum security guards.

“This is absolutely meant to be a nonviolent protest,” said Slater. “It’s about peacefully taking back of democracy and ending the war in Afghanistan.”

St. Thomas said that the Air and Space Museum will open at its regularly scheduled time of 10 a.m. Sunday.