Unexploded World War II munitions, debris and bomb fragments washed up on Assateague Island National Seashore, just south of Ocean City, Md., this week, shutting down the popular pure-white beaches until they were exploded late Tuesday night, according to state officials.

On Tuesday, the park announced on Facebook that it had unexpectedly closed to beach goers and campers. "Due to unexploded WWII ordnance that has washed up on the beach, there is no access to the national seashore at this time. You may still access the state park. Check back for updates." The state park sits between the national park to the south and the Ocean City inlet to the north.

Later, after a federal disposal team from Aberdeen, Md., home to the Aberdeen Proving Ground, exploded the bombs, park officials returned to Facebook with this message: "The National Seashore has reopened! There is limited parking in the North Beach parking lot, as part of the lots is still closed. Thank you for your cooperation and patience!" They posted a video of the explosion on their Facebook page.

Officials said about 100 munitions and part of bombs washed up Monday or Tuesday and were found by visitors.

It's likely that the old ordnance was from the U.S. Navy which used the barrier island as a target range during World War II. After the war, "an ordnance burial site" was built on part of the island that has since been reclaimed by the ocean.

Paul Bedard, The Washington Examiner's "Washington Secrets" columnist, can be contacted at pbedard@washingtonexaminer.com.