U.S. Border Patrol agents arrested a trucker Friday evening after discovering 33 undocumented immigrants locked inside a refrigerated trailer.

Agents referred the driver of the tractor-trailer to a secondary inspection at about 9:30 p.m. at the Falfurrias Border Patrol Checkpoint. 

During the inspection, agents discovered the immigrants inside the refrigerated trailer, which was 53 degrees Fahrenheit. The trailer was also carrying a mixed load of cucumbers and peppers, according to a news release by U.S. Customs and Border Protection.

The immigrants were offered medical attention, which they all declined.

Agents arrested the driver on charges of human smuggling, according to the news release. The case was handed over to the Rio Grande Valley Sector Prosecutions Office.