If you believe border walls will keep migrants out, look carefully at the photo above. It was taken by the U.S. Border Patrol. What you’re seeing is a tunnel under the border fence near San Luis, Arizona. Migrants dug seven of them this week, and through those tunnels came the largest single group of asylum seekers ever to cross into the United States, according to ABC News.

376 migrants crawled under and over the wall. The number included nearly 200 minors.

“The mass crossing this week took place in a sparsely populated stretch of the border — where an old model of border barrier rises about 12 feet from the sandy ground. The stretched agency only had three agents patrolling that 26-mile-long section of the border. “It took hours to process the families, most of which were sent to the area’s chronically overcrowded central processing center in Yuma. “In my 30 years with the Border Patrol, I have not been part of arresting a group of 376 people,” Porvaznik said. “That’s really unheard of.”

Largest single group of migrants ever tunnels under border wall in Arizona, says Border Patrol. https://t.co/O7aBPm9gnr pic.twitter.com/apow2qJI5I — ABC News (@ABC) January 18, 2019

Watch the video from ABC News in the link above.