Police in Hayward, California are investigating a shooting that left a 10-year-old girl wounded, because bullets went through her bedroom wall. And her parents didn't even realize she was injured—the girl and her parents thought she had just had her period.

The shooting occurred around 2 a.m. on Thursday morning, and bullets hit the house on Tampa Avenue as well as a car parked outside. But the family didn't call the police until five hours later, which puzzled the police. Sgt. Mark Ormsby said, "If they know shots are fired and you know that your child has been hit, that would be something that I would absolutely say you have a responsibility to call the police."

Now it turns out, the girl, who was shot in the buttocks, was in pain but thought she was having her period. From the SF Chronicle:

The family contacted its doctor, who confirmed that the bleeding could be consistent with a period, Ormsby said. And there were no clear signs the girl had been shot when her family took her to the bathroom to clean her.

About 7:30 a.m., when the girl awoke, she was still in pain, unaware that the bullet "was lodged in the pelvic area," Ormsby said.

The parents then inspected her bed and saw bullet holes. They did a "full body inspection" of the girl, found an entry wound and immediately called 911, Ormsby said.

Investigators later spoke with the family's doctor and confirmed that the entry wound was "rather small" and could have been overlooked if they thought she was starting her period, Ormsby said.

Police are still investigating the shooting.