Fox News reports a tragic scene unfolded this afternoon near the Texas-Mexican border as "12 people were ejected from an SUV carrying illegal immigrants after it crashed following a high-speed chase with U.S. Border Patrol vehicles".
Four people were pronounced dead at the scene while a fifth died at a hospital.
Boyd said the vehicle was going more than 100 miles per hour before the crash.
This article be updated as more details become available.
Dimmit County Sheriff Marion Boyd said "good police work" was the reason why deputies started pursuing the vehicle.
Some of the wounded were thrown from a auto packed with 14 people that was travelling at 100mph (160km/h), County Sheriff Marion Boyd told KFDM News TV.More news: Migrant ship Aquarius to dock in Spain
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High-speed chases aren't uncommon in some US states bordering Mexico, as smugglers and others attempt to flee checkpoints and outrun the Border Patrol.
Almost 2,000 children have been taken from their parents since the Trump administration announced its "zero tolerance" policy against people entering the US without legal permission.
A Border Patrol agent observed three vehicles traveling one behind the other on FM 2664 and suspected a smuggling attempt was happening, the agency said in a statement.
Boyd said the driver and one passenger of the passengers were the only USA citizens in the vehicle. "I think we need a wall in my opinion". The weight of the people causes the vehicle to become unstable and makes it easy for crashes to occur, Border Patrol officials previously told Breitbart Texas.
The crash comes amid heightened tensions over the treatment of immigrants at the southern border.
They are likely to face state and federal charges, Boyd said.