Aaron was with his dad Alan and little sister Abby waiting for mom Katherine to cross the finish line when the explosions happened. It was instant chaos.
Alan grabbed his daughter and ran up the street, but soon realized Aaron was not with them.
"I found him on the sidewalk on his back with some other people who were injured he was conscious, he talked to me and said, 'My leg really hurts, daddy,' but he was being pretty brave," Alan said.
Aaron's grandmother Catherine says he was so close to the second bomb that it singed his hair.
"His hair was singed, his ear was a little red, his eye was swollen and i think they did the initial cleanup to where the shrapnel hit him," she said. "He had a lot of other abrasions."
Someone used a belt to make a tourniquet for Aaron's leg. Once at the hospital, the family heard from his doctors.
"He was doing well considering that it was a major wound, but it was going to be alright, he has no injuries to anything vital, nothing broken no arteries were cut," Alan said.
Aaron's family remains by his side as he recovers.
Back at home, Aaron's classmates at Martinez Junior High School are taking action to help, while administrators and parents do their best to comfort the student body.
"He said that, you know, he's just kind of, you know, sad for him and then my nephew is real good friends with him and he was real upset and stuff. So I think the kids are having a hard time with it. As are the parents," parent Steve Lipary said.
A crisis intervention team was on the MJHS campus Tuesday and school officials are doing what they can to help.
"We sent out an all-call to parents through a robo-call to let folks know because there's so many people who know the family in many ways," Superintendent Rami Muth said. "[Aaron's father] is our high school varsity football coach, and so, you know, they're very much a part of the fabric of this community."
Students pulled together to support the Hern family by wearing purple to school Tuesday.
"Everyone in her class is going to be wearing purple for [Aaron]. And they've already started to contact each other you know, by the Facebook, and the internet and all this stuff that's going on," said Grandmother Valerie Donelson.
Teachers and students are looking for other ways to help the Hern family; including raising money to help pay for the Hern's extended stay in Boston to making a video to show their support for Aaron.