Photo: The Canadian Press

Arapahoe County Sheriff Grayson Robinson holds a picture of Claire Davis, the 17-year-old student who was shot in the head by a classmate, during a briefing at Arapahoe High School in Centennial, Colo.

A suburban Denver high school student who was shot in the head by a classmate died Saturday afternoon, hospital officials and her family said.

Claire Davis, 17, was in critical condition after being shot at point-blank range at Arapahoe High School on Dec. 13.

"It is with heavy hearts that we share that at 4:29 p.m. this afternoon, Claire Davis passed away, with her family at her side," a statement from Littleton Adventist Hospital said.

"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."

The Davis family said they appreciated the outpouring of support from the community and thanked the efforts of law enforcement, school officials and medical staff.

Friends and well-wishers had posted prayers online and raised money to help pay for Claire Davis' medical care in days following the shooting.

The Denver Foundation said a fund had been created honouring her that would support the high school and community in programs for mental health, anti-bullying and other needs.

Karl Pierson, 18, shot Davis, who just happened to be sitting nearby with a friend as Pierson, armed with a shotgun, ammunition strapped to his body, Molotov cocktails and a machete, entered the school and headed toward the library. Davis appeared to be a random target, Arapahoe County Sheriff Grayson Robinson has said. 

Pierson likely intended to track down a librarian who had disciplined him, but Robinson said Pierson's arsenal suggested Pierson intended to hurt many others at the school just eight miles (13 kilometres) from Columbine High School, the site of a 1999 massacre in which two student gunmen killed 12 students and a teacher before killing themselves.

Pierson set off one of the incendiary devices and fired five shots before killing himself just one minute and 20 seconds after entering the building. He knew a sheriff's deputy assigned to the school was closing in, Robinson said at a news conference.

Pierson's original target was believed to be a librarian who coached the school's speech and debate team. Pierson was a skilled speaker and debater on the team. The librarian, whose name was not released, had disciplined the teen in September for reasons that haven't been disclosed. Robinson said Pierson had made some sort of threat against the librarian in September.

The librarian was able to escape the school unharmed, Robinson said.

Pierson legally purchased his shotgun at a local store a week before the shooting and bought the ammunition the day of the shooting. Anyone 18 and older is allowed to buy a shotgun in Colorado; only those over 21 can legally buy a handgun.

The Arapahoe shooting came a day before the one-year anniversary of the Newtown, Connecticut, attack in which a gunman killed 20 children and six adults at Sandy Hook Elementary School.