"We did not hear anybody say they intended to kill her, but could they have accidentally killed her? Absolutely," Tanner said. "We feel like if they weren't interrupted, there would have been an attempt. Would they have been successful? We don't know."
This, mixed with a little creative licence. I'm shallow and I want people to post in my threads.
As for the whole grade thingie; inter-cultural awareness and understanding is always good, but it took me (a fellow limey) all of four seconds to google-check it. It also does state their age in the article, so... *shrugs*