A 17-year-old girl is in critical condition after authorities say she was shot at point-blank range by an 18-year-old gunman at Arapahoe High School in Centennial, Colo. Friday afternoon.

At a news conference Saturday, Arapahoe County Sheriff Grayson Robinson identified Claire Davis as the victim and read a statement from her family saying that first responders and a trauma team at nearby Littleton Adventist Hospital had saved her life, but she was suffering from severe head trauma.

"She needs your continued prayers," part of the statement read.

Students and residents held a candlelight vigil for Davis Saturday night at a park near the school. Friends and well-wishers posted prayers on Twitter, and some students collected money to help pay for her medical expenses.

"I feel like it's going to make us a stronger senior class and school as a whole," said Chris Davis, an Arapahoe senior who is not related to Claire Davis and helped organize the fundraising effort. He said she has a lot of friends, always seems happy and loves horses.

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Colorado Gov. John Hickenlooper told CBS television's "Face the Nation" Sunday that he had visited Davis and her family and that she was in a coma. "Her parents are two of the most wonderful people you could ever hope to meet," he said. "I just can't imagine what they're going through. It's unspeakable."

Robinson called Claire Davis a young woman of “principle” and “purpose.”

“She is an innocent young lady and she was an innocent victim of an evil act of violence," he said.

Authorities said that the gunman, identified as Karl Pierson, had entered the building with a shotgun, a machete and three Molotov cocktails in his backpack, and planned to hurt multiple people.

“It is our strong belief that he came to the school with that weapon and with multiple rounds … to cause harm to a large number of individuals,” Robinson said. ”His intent was evil.”

Robinson said Pierson likely was motived by retaliation against a faculty member – believed to be librarian and debate coach Tracy Murphy -- when he opened fire Friday.

Robinson also said that the teen had bought the pump-action shotgun legally Dec. 6 at a local store. In all, the sheriff said Pierson fired six shots from his weapon, including the shot that killed him. Three of the shots were random blasts down the school's hallway.

Pierson was reportedly targeting Murphy because he had recently kicked him off the school’s debate team.

Pierson was disciplined in September by the librarian for reasons Robinson said were under investigation. Pierson made some sort of threat in September against the librarian, according to The Associated Press.

Students and a teacher said Pierson was an Eagle Scout who finished at the top of speech competitions. He competed in extemporaneous speaking — in which students prepare short speeches on current events — in the National Forensic League's national tournament in June in Birmingham, Ala.

"I think he (Pierson) really cultivated his speech and argument skills and really thought that was a big part of his identity," said Steve Miles, an English teacher who taught Pierson as a freshman. "He probably thought it was a pretty crushing blow to get kicked off the debate team."

KDVR.com reported that a student at Arapahoe High School in Centennial said Pierson was in a "rage" on Wednesday and yelled at one of his teachers.

"Apparently that was enough to set him off," the student said.

Robinson said that after Pierson entered the high school at approximately 12:33 p.m. Friday, near the student parking lot, he asked for the teacher by name. At one point, Pierson went into the library, where Murphy actually was located, but a janitor initiated a lockdown and Murphy was able to escape as Pierson entered the room.

After that, Pierson set off one of the Molotov cocktails, setting at least three bookshelves on fire, investigators told KDVR.com. When an armed school resource officer entered the room, Pierson believed he was cornered and turned his gun on himself, Robinson said. The entire attack lasted approximately 80 seconds and was captured by security cameras.

Pierson's body remained inside the school Friday night, Robinson said, "because it is part of a crime scene investigation." Robinson said he did not know if the student was enrolled in Murphy's class.

"He knew he was the target and he left that school in an effort to try to encourage the shooter to also leave the school," the sheriff said. "That was a very wise tactical decision."

Authorities also said Saturday that a second student who had been taken to a hospital with blood on her after the shooting was not physically injured.

Davis, Robinson said, appeared to be a random target.

Pierson, whose parents are divorced, lived at least part of the time with his mother in a higher-end neighborhood in suburban Highlands Ranch. The front door of the home was covered with plywood Saturday after authorities conducted a search.

Students said he was a smart, funny and sometimes goofy student who sometimes debated his teachers.

"He would speak for himself," said Zach Runberg, 18, a senior in Pierson's English class. "He would not be afraid to tell someone how he feels."

The Associated Press contributed to this report.

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