This is an archived article and the information in the article may be outdated. Please look at the time stamp on the story to see when it was last updated.

Please enable Javascript to watch this video

WESTMINSTER, Colo. -- A student walked into the Standley Lake High School cafeteria on Monday morning and set himself on fire, causing severe injuries to himself and causing the evacuation and closure of the high school.

The Westminster High School was open Tuesday only for students to come back and retrieve items they may have left behind in the evacuation. Classes remained cancelled, but counseling services were being offered for students.

A 16-year-old sophomore walked into the school around 7 a.m. on Monday, and used a one-gallon can of Coleman fuel.

"I saw this explosion happening in the lunch room," Leif Samson said. "Everyone started running out screaming, 'Fire!' I just grabbed my backpack and ran upstairs, and I looked out the windows overlooking the cafeteria. That's when I found out it was a guy on fire."

Two employees used a fire extinguisher to put out the fire quickly, according to Westminster Police spokeswoman Cheryl Spottke, but not before the student suffered severe burns. One of the first emergency responders estimated he had third degree burns over 80 percent of his body.

Police believe the student only intended to harm himself.

"We do believe that this was a suicide attempt we don't have any indication at this point that there was a threat against Standley Lake High School or any other school in Westminster," Spottke said.

"This is just such a tragedy," Jefferson County Schools spokesperson Lynn Setzer said. "Our hearts and our prayers go out to the family and to the school community and to the students who were here (Monday) morning."

Investigators later searched Nett's home, where they learned about a suicide note posted on Facebook that claims he had been planning his own public death for years.

"We're in high school," a girl who knew Nett said. "No life should end or even think about ending like this. It's so wrong to think that I'm not going to see him or talk to him again."

One of the cafeteria workers also suffered minor injuries when she broke the glass to access the fire extinguisher, Spottke said. Spottke also confirmed there were students in the cafeteria who witnessed the student lighting himself on fire.

Nett was taken to a hospital right away Monday morning. He was in critical condition. Friends left flowers outside his home, wondering if they could've helped.

Jefferson County Schools has not said when classes will resume at Standley Lake.