Tonight on AC360: Shooting survivor hopes for another "miracle"

Colorado shooting survivor Petra Anderson is beating the odds. She's already walking and telling jokes after being shot four times in theater 9 of the Aurora multiplex just 11 days ago. Three shotgun pellets hit her arm, and one went through her nose into her brain.

"She's so amazing, she's so determined, " Petra's mother, Kim, told CNN's David Mattingly.

You might remember, in the days following the massacre, there was talk that Petra had an unusual brain malformation that allowed her to survive that shotgun wound to her head. Doctors called it a "miracle." They still do, but there's no more talk of a brain malformation. They say amazingly the bullet hit at just the right angle to avoid causing catastrophic damage. If it had struck just one millimeter to the left or right there would be no talk of a "miracle." Instead, they'd be mourning her death. Thankfully, Petra is a survivor.

Petra, a 22-year-old aspiring composer, hopes to pick up her violin again and even go to graduate school for music this fall. But her ultimate goal is another "miracle" - one for her mother, who's battling cancer. Petra wants her mom to survive alongside her.

At 8 and 10 p.m. ET tonight, don't miss David Mattingly's report on Petra and her mom, followed by 360 M.D. Sanjay Gupta, a practicing neurosurgeon. He shows us how Petra is fighting to recover - with some help from music.