Border Patrol agents in Arizona found two unaccompanied minors and 16 other migrants locked in the back of a box truck without food, water, fresh air, or means of escape. The discovery came in the middle of a hot Arizona summer Saturday.

Agents assigned to the Brian A. Terry Station witnessed a group of suspected illegal immigrants walking through the desert about a mile from the Mexican border near Hereford, Arizona, on Saturday afternoon. They also observed the driver of a box utility truck making frequent stops along a road in the same area, according to U.S. Customs and Border Protection officials.

Additional agents continued to observe the truck as it began to leave the Coronado National Memorial area just south of Sierra Vista, Arizona. After following the truck for a short distance, the agents activated their emergency lights and initiated a traffic stop for an immigration inspection. The truck quickly stopped and an agent approached the driver and requested permission to look in the back of the vehicle. The driver stepped out and opened the rear door.

The agent found 18 people locked inside with no means of escape in the event of an accident or overheating. Agents said the truck had no source of light, no water, and no ventilation or air-conditioning.

Agents reported the migrants included two unaccompanied Mexican children, 13 Mexican nationals, and three Guatemalans.

The agents arrested the driver on charges connected to human smuggling activities. They transported the driver and the 18 migrants to the Brian A. Terry Border Patrol Station just north of Naco, Arizona, where they will be processed.