Some 150 people were found crammed into the back of a tractor trailer at a border checkpoint near Laredo, Texas, according to federal prosecutors. The driver, identified in a criminal complaint as Joseph Winslow, is charged with “bringing in and harboring certain aliens.”

Winslow’s human cargo was made up at least partially of people from Mexico and Venezuela, according to the filing, which says that Winslow, a Florida resident, not only isn’t licensed to drive big rigs, but doesn’t have a driver’s license at all. He stopped at an inland Border Patrol checkpoint along Interstate 35 on Dec. 30, the filing reveals. When agents asked what he was transporting in his truck, Winslow allegedly replied that he didn’t know. After x-raying the vehicle and finding anomalies, agents opened the trailer and discovered the migrants. Winslow said he’d been paid $100 for the job, with the promise of $10,000 more once he arrived in San Antonio with his load.

Border Patrol has described an increase in human smuggling cases involving tractor trailers. In May, 36 people were found hidden in a tractor trailer at the same I-35 checkpoint. A few months earlier, 26 people were discovered in a tractor trailer in California. In 2018, a Texas trucker carrying dozens of immigrants—10 of whom died—was sentenced to life in prison for the deaths.