The crash happened on the US 281 in Encino, Texas, about 180 miles south of San Antonio.
Sergeant Nathan Brandley of the Texas Department of Public Safety said the van, designed to hold 15 passengers, was speeding as the driver tried to veer off the road onto Business Route 281.
A further 20 passengers were injured in the crash at around 4pm on Wednesday.
Texas Department of Public Safety officers (The Monitor/AP)
The driver lost control of the top-heavy van, which crashed into a metal utility pole and a stop sign.
The van was not being pursued, authorities said.
Brooks County Sheriff Urbino Martinez said he believed all of the passengers were migrants.
At least 10 dead in Texas road accident near Mexico border dunyanews.tv - get the latest breaking news, showbiz & celebrity photos, sport news & rumours, viral videos and top stories from dunyanews.tv Daily Mail and Mail on Sunday newspapers.
Ten people were killed and 12 injured on Wednesday when a van carrying 25 migrants crashed in southern Texas, about 90 miles (150 km) from the United States-Mexico border, local media reported.
10 killed, 20 injured in Texas crash of overloaded van carrying migrants
An overloaded van carrying 29 migrants has crashed on a remote South Texas highway, killing at least 10 people, including the driver, and injuring 20 others, authorities say.
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The Associated Press ·
Posted: Aug 05, 2021 1:33 AM ET | Last Updated: August 5
Texas Department of Public Safety officers pick up debris near a vehicle where multiple people died after the van carrying migrants tipped over just south of the Brooks County community of Encino on Wednesday.(Delcia Lopez/The Monitor/The Associated Press)