Officials say 46 people were found dead in and near a tractor-trailer and 16 others were taken to hospitals in a presumed migrant smuggling attempt into the United States.
Police Chief William McManus said a city worker at the scene was alerted to the situation by a cry for help shortly before 6 p.m. Monday.
He said officers arrived to find a body on the ground outside the trailer and a partially opened gate to the trailer.
Fire Chief Charles Hood said 12 of those taken to hospitals were adults and four were children.
He said they were hot to the touch and dehydrated, and no water was found in the trailer.