RICHMOND, Calif. -- On Oct. 24, police say dozens of teens gawked, laughed and took photographs while a 15-year-old girl was brutally gang-raped and beaten outside a Richmond High School homecoming dance.

But one brave girl, who was not even there, wouldn't stand for it.

"I was watching a movie, and my brother-in-law came in and he told me 'I don't know what to do, because there is a girl back there and she has been raped. I'm scared,'" 18-year-old Margarita Vargas said.

"I'm like 'We should call the cops because that's the right thing to do.' I didn't think about it twice."

Vargas said she called police because she would want someone to do the same if she ever was in that situation.

After making the call, Vargas went to the scene to check on the girl.

"I could tell that she had been beat up because her face was swollen," Vargas said. "She was naked, didn't have shoes.