A 10-year-old California girl wasn’t treated for a gunshot wound for more than five hours after her parents thought she was having her period instead.

The girl, who was not identified but lived in Hayward, Calif., was sleeping around 2 a.m. Thursday, when someone shot up her home, police told the San Francisco Chronicle on Friday. She suffered a gunshot wound to the buttocks.

The 10-year-old initially thought she was having her period when she woke up later that morning with pain, Hayward Police Department Sgt. Mark Ormsby told the Chronicle. The girl’s suspicions were also confirmed by a doctor, who said the bleeding could be consistent with the 10-year-old having her period.

After waking up a second time to get ready for school, her parents checked her bed and discovered bullet holes, the Associated Press reported.

A “full body inspection” of the girl found the bullet’s entry wound, Ormsby told the Chronicle. The girl’s parents then called 911.

The family doctor said the entry wound was “rather small” and that it was possible for the parents to believe their daughter was having her period if the wound was never found.

The girl was in stable condition at a local hospital, as of Friday.

Investigators are trying to determine a motive for the shooting. Authorities are unsure whether the home was specifically targeted or if the perpetrators shot up the wrong house.