Student critically wounded in Colorado school shooting; suspect dead

Law enforcement officials are investigating a Colorado high school shooting that left one teenager critically wounded and may have involved a student seeking to confront one of his teachers.

The suspect, a student identified as 18-year-old Karl Halverson Pierson, apparently took his own life following the incident, officials said.

Arapahoe County Sheriff Grayson Robinson told reporters at a news conference Friday evening that a 15-year-old girl suffered what he described as a "significant" gunshot wound during the incident at Arapahoe High School in Centennial, Colo., about 15 miles south of Denver.

"Our thoughts and our prayers are with that dear young lady and her family," Robinson said. 

That student remains hospitalized in critical condition. Earlier news reports had indicated that three students had been injured. The total was later revised to two, but Robinson said the second student – initially believed to have been shot – was found to have blood on her from the wounded 15-year-old.  

Robinson said preliminary information indicated that the shooter was seeking out a teacher with whom he may have had a dispute.

"We believe his motive may have been a reaction to that disagreement or confrontation," Robinson said. 

He said the suspected gunman "identified a specific teacher at Arapahoe High School that he was interested in confronting, and that teacher was informed of the situation and exited the school quickly.”

When the teacher learned that he was being targeted, he left "in an effort to try to encourage the shooter to also leave the school," Robinson said. "That was a very wise tactical decision."

The suspected shooter was later found dead inside the school after he "apparently killed himself," the sheriff said.

Robinson also said that two Molotov cocktails were found inside the school, and that one was detonated. 

The deceased suspect is believed to be the lone actor in the shooting, but officials were still investigating. Robinson said the investigation would focus on attempting to determine what happened and why. 

"We will do it right, we don't do it quick," he said. "It will be our responsibility and purpose to interview every possible, conceivable witness." 

Robinson said four areas have been identified as crime scenes to be investigated: the high school, the suspect's vehicle and home, and his father's home in Denver.

Television images from the Colorado high school during the incident showed students running out with their hands raised and gathering on a track field. Some were shown being patted down in the aftermath in single-file lines. 

Robinson said shortly after the incident that officers in Colorado were "slowly and methodically" clearing the school and transporting students by bus to a nearby church. He said the entire incident lasted 14 minutes.

Senior Megan Jeffords, 18, was singing Christmas carols in the hall with her choir class when the shots rang out. A teacher rushed the 18 singers into a closet, where they huddled for more than half an hour.

Hours later, after Jeffords was reunited with her father, she was still visibly shaken and unable to talk much about what happened.

Jessica Girard was in math class when she said she heard three shots.

"Then there was a bunch of yelling, and then I think one of the people who had been shot was yelling in the hallway, `Make it stop,'" she said.

The incident came a day before the first anniversary of the mass shooting in Newtown, Conn., in which a gunman killed 20 children and six adults at Sandy Hook Elementary School before killing himself.

The town of Centennial is not far from the unincorporated community in nearby Jefferson County that is home to Columbine High School, where two students gunned down 13 classmates and staff before killing themselves in 1999.

Al Jazeera and wire services