(CNN) -- A 15-year-old high school sophomore, accused of holding 23 classmates and a teacher hostage at his Wisconsin school on Monday, fired his two weapons at least five times, police believe, and had a duffel bag containing more bullets with him, authorities said Tuesday.
The teenager was being treated for a "potentially life-threatening" self-inflicted gunshot wound. He shot himself when officers approached him Monday evening, Marinette, Wisconsin, Police Chief Jeff Skorik told reporters. He said he did not know whether the youth remained hospitalized, but "as far as we know, he's in serious condition." Skorik would not identify the suspect because of his age.
All 24 hostages were unharmed after the incident. Skorik Tuesday said police are still trying to determine a motive, saying the student was well-liked, had no prior law enforcement contact and "was a good student."
Marinette, Wisconsin is located approximately an hour's drive north of Green Bay, Wisconsin on the shores of Lake Michigan.