FORT WORTH — Fort Worth police say they're trying to determine how a one-year-old ingested Xanax, a prescription drug used to treat anxiety disorders and panic attacks.

Police were called to Cook Children's Hospital Monday morning, where they met with a Child Protective Services worker and the infant girl's mother.

The mother told them the baby's 24-year-old father picked the child up on Sunday evening, then called to say he was taking her to the hospital because she had swallowed half a tablet of Xanax.

Hospital employees also learned the infant had been exposed to marijuana, police said. The father left the hospital before the officers arrived.

The one-year-old's mother told police the child's father had smoked marijuana in the past.