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"I just heard what I though were fireworks and burning rubber," said eyewitness Lucina Velasquez.
Police say a suspected gang member standing across the street from the teenager's home was shooting at a dark-colored pickup truck as it drove by when one of the bullets hit the teen inside her home.
The girl's mother then makes this frantic 911 call.
"Hello? Can you send somebody? There's been a shooting outside in the street and my daughter's been hit, please!" The operator says: "OK, where is your daughter right now?" The mother answers: "In the bedroom. Come on."
"The victim was struck once in the torso by a stray bullet -- the 5-month-old was injured by what appears to be flying glass," said Corporal Jose Gonzalez, Santa Ana Police.
"It was my friend. I never expected ... she never hurt anyone in her life, she was such a good girl, never done anything," said the victim's friend Jocelyn Cruz.
"That was messed up because the girl never did nothing to them," said neighbor Angelica Ortiz.
Fortunately the teenager and her sister survived. Shootings like this, unfortunately, are not surprising to some people.
"They like to do drive-bys often," said neighbor Hector Hernandez.
"There is a particular gang that claims the area as territory, we're not releasing name so don't glorify," said Cpl. Gonzalez.
Police hope someone will come forward with information to find the suspect.
"It's bad, awful, people shouldn't ... a lot of kids playing ... and they get shot without any reason," said Velasquez. "It's awful."