An 8-month-old boy who suffered a massive skull fracture, allegedly at the hands of his mother’s boyfriend, remains hospitalized.

San Antonio police arrested Julian Garza, 19, in connection with the injury that the baby, Steven Ybarra, suffered Monday.

According to an arrest warrant affidavit, Garza told police he was babysitting the boy in their home in the 200 block of Bustillos Drive when the injury happened.

The affidavit stated that Garza said he became angry because the baby was restless and “wouldn’t let him sleep."

He said at one point, he threw his arms up, causing Steven’s head to hit a window sill, the affidavit stated.

Police said that a doctor at the Children’s Hospital of San Antonio described the baby’s injury as “a massive skull fracture.”

The affidavit also stated that Garza did not seek treatment for Steven right away, or tell the baby’s mother about the injury.

He told police he feared that his girlfriend might become angry, or that he would get into trouble with the law, the affidavit stated.

Garza was booked into the Bexar County jail Tuesday on a charge of injury to a child.

Bond for him was set later at $30,000.

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