ALAMOGORDO, N.M. — Like kids who can't resist looking at Christmas presents behind a closed closet door, hundreds of unauthorized visitors climbed a dune-covered fence Monday to gain access to White Sands National Monument, officially off limits because of the federal government shutdown.

On Monday, a line of cars was parked along the perimeter of the monument where the dunes come closest to the road a couple of miles southwest on U.S. 70 from the monument's visitors center. Fencing separates the monument from the highway, but families could be seen on the other side of the fence playing on the dunes, taking selfies and riding sleds.

“We were going to El Paso but we spent a night in Las Cruces so we could come here,” said Mihir Trivedi, taking a trip with his wife from California to New Orleans. They found out that the park was closed about a half hour before they arrived at the front gate.

“If I would have known, we would have gone to El Paso and then to San Antonio," he said. "This and New Orleans are what we were most excited about.”

► Dec. 24:NORAD's Santa Tracker won’t be affected by government shutdown

► Dec. 24:Trump complains he's all alone waiting for Dems to deal end to shutdown

► Dec. 24:Sen. Bob Corker calls reasoning for shutdown a 'made-up fight'

The monument, established in 1933, is about 70 miles north of El Paso, Texas, and 15 miles southwest of Alamogordo. The cost to visit is normally $5 for those ages 16 and older and free for those younger than 15.

One family came to the dunes from Oklahoma for a very specific reason, even knowing that White Sands is closed.

“We came here to get one picture to pose for the (Oklahoma City) Thunder game tomorrow, so we’re going to take a picture and that’s it,” John Block said.

Crew members from the New Mexico Department of Transportation were dispatched to the area late Monday morning to put up flashing “No Parking” signs because cars were parking on either side of the highway and walking across the road to get to the dunes.

Visitors had been using the ersatz entrance since the park was closed Saturday, the one state Transportation Department employee said. Because Saturday was a full moon and the park hosts nighttime walks during full moons, a lot of people were walking through the park at night.

The 224-square-mile national monument is south of the U.S. Army's White Sands Missile Range, 3,200 square miles where testing of the first atomic bomb took place in 1945.

The National Park Service has jurisdiction over White Sands National Monument, according to New Mexico State Police. But because of the government shutdown in its third day, White Sands’ federal staff weren't out patrolling and couldn't be reached for comment.

Although many other national parks and monuments are remaining as accessible as possible during the shutdown, albeit without open restrooms and visitors centers, White Sands is completely closed, according to the National Park Service.

Follow Dylan Taylor-Lehman on Twitter: @theyawningchasm