"It is with heavy hearts that we share that a 4:29 p.m. this afternoon, Claire Davis passed away, with her family at her side," Littleton Adventist Hospital said in a statement.
"Despite the best efforts of our physicians and nursing staff, and Claire's fighting spirit, her injuries were too severe and the most advanced medical treatments could not prevent this tragic loss of life. Claire's death is immensely heartbreaking for our entire community, our staff and our families."
Police identified her shooter as Karl Pierson, the 18-year-old Arapahoe High School senior who then shot himself on December 13.
"We cannot begin to understand why Karl did what he did," the shooter's parents, Barbara and Mark Pierson, said last week in a statement. They also offered prayers "for the entire Arapahoe High School community, as we know your lives are forever changed by this horrific event."
Police say Pierson was looking for revenge against a librarian, but couldn't find the faculty member and killed himself as a school resource officer closed in. Davis did not know the shooter and was just a random victim, police surmised.
Hundreds of people attended a vigil for Davis last Saturday.