WASHINGTON — U.S. Border Patrol agents found a 3-year-old migrant alone in a cornfield at the border between Mexico and Texas on Tuesday morning, according to Customs and Border Protection officials.

The boy, who was crying when agents found him in the Rio Grande Valley near Brownsville, Texas, was identified only by a phone number and his name written on his shoes, the officials said.

The agents have taken the boy to a U.S. border station and are trying to find his parents using the number on his shoes, the officials said. So far, they have been unsuccessful and are in the process of transferring the boy to the care of Health and Human Services.

A U.S. border agent carries a three-year-old boy who U.S. Customs and Border Protection says was found in a cornfield in the Rio Grande Valley near Brownsville, Texas, on April 23, 2019. U.S. Customs and Border Protection

Rudy Karish, the chief Border Patrol agent in the Rio Grande Valley, said he believes the boy was left by smugglers. Karish said he believes the boy was with a larger group. When the group was encountered by agents, the adults ran away and left the boy alone.

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The boy watched movies at the border station and appears to be in good spirits, Karish said.

The incident marks a flashpoint in the rising number of families and children crossing the border in recent months. In March, a total of 8,975 children traveling without their parents, but most often in groups, were apprehended at the southern border. The number of families crossing has also climbed, with 53,077 parents and children crossing the border together last month.

In December, two young children died in Customs and Border Protection custody shortly after reaching the United States with their parents.

The journey into the Rio Grande Valley of Texas has long been an arduous but popular one, with immigrants risking dangerous waters to float or swim across the river from Mexico to Texas.

Border agents are still looking for the boy's parents or anyone who may be able to provide more information.