A 10th person has died after being discovered in the back of a sweltering tractor-trailer in Texas.
Around 20 others were taken to hospital in a "dire" condition after they were found in the truck parked outside a San Antonio Walmart early on Sunday.
A man who was arrested over the incident is due to appear in court.
Federal prosecutors say James Mathew Bradley, 60, of Clearwater, Florida, will face charges. He is believed to have been the driver, although this has not yet been confirmed.
Around 20 other people rescued from the back of the rig were said to be suffering from extreme dehydration and heatstroke.
Foreign officials from Mexico and Guatemala confirmed people from those countries were found in the abandoned tractor-trailer.
US Immigration and Customs Enforcement acting director Thomas Homan said the truck driver is in custody.
The local US Attorney's Office would not say whether Bradley was the alleged driver who was arrested.