Texas Gov. Greg Abbott is blaming President Joe Biden’s "open border policies" for the deaths of 50 people in a tractor-trailer near San Antonio.

Abbott made his comments in a Monday night tweet, writing: "At Least 42 People Found Dead Inside Truck Carrying Migrants In Texas. These deaths are on Biden. They are a result of his deadly open border policies. They show the deadly consequences of his refusal to enforce the law."

Since then the number of reported deaths has increased. More than a dozen people were hospitalized.

NBC News reported Mexican President Andrés Manuel López Obrador put the death toll at 50. He said 22 of the dead were Mexican nationals, seven were from Guatemala, and two were from Honduras. Nationalities of the other 19 had not been confirmed, according to NBC News.  

The truck had been abandoned on a remote road in San Antonio.

Reuters reported Police Chief Willian McManus said a city worker heard a cry for help from the truck before making the deadly discovery.

Those inside the tractor-trailer most likely died due to heat stroke or heat exhaustion as they were trapped inside a tractor-trailer in 100-degree weather, said San Antonio Fire Chief Charles Hood, according to The Epoch Times.

The White House declined to directly respond to Abbott’s tweet.

But the Washington Examiner reported that press secretary Karine Jean-Pierre said: “The fact of the matter is, the border is closed, which is in part why you see people trying to make this dangerous journey using smuggling networks.

"Our hearts go out to the families at this time. We are going to stay focused on the facts and making sure we hold these smugglers accountable."