Mexican officials have now released fascinating images that show the desperate measures that some people are taking to try to sneak into the U.S.

The image above is the X-ray taken by Chiapas state police examining trucks at a checkpoint in the outskirts of city of Tuxtla Gutierrez that revealed 513 migrants crammed into two trailers bound for the United States. It’s not clear how many dozens were in this single trailer.

Some of the immigrants were suffering from dehydration after traveling for hours clinging to cargo ropes strung inside the containers to keep them upright as the trucks bounced along from the Guatemalan border, and allow more migrants to be more crammed in on the floor.

In this image released by the Chiapas State Attorney General, the migrants are unloaded from one of the trucks.

The AP reports that the migrants said the smugglers were charging them about $7,000 apiece to get them into the United States. Federal officials said 410 of the migrants were from Guatemala, 47 from El Salvador, 32 from Ecuador, 12 from India, six from Nepal, three from China and one each from Japan, the Dominican Republic and Honduras. Most were men; there were 32 women and four children.