BOULDER – The sheriff's deputy who was first on the scene would have been justified using lethal force against a knife-wielding man at the University of Colorado who cut a student's neck, stabbed himself and terrorized observers on the morning of the first day of class Monday, Boulder County Sheriff's Office Division Chief Dennis Hopper said.

Hopper said Deputy Stuart Holt, a veteran officer, had to make quick decisions as the incoherent suspect – whom CU police identified as 39-year-old Kenton Astin of Boulder, waved a steak knife over his head and said he had a bomb.

"The officer used restraint," Hopper said. "If deadly force was used it probably would have been justified."

Hopper said if the suspect had begun approaching other students instead of stabbing himself, the outcome could have been much different.

Hopper said Holt was off-duty working traffic patrol on his day off at a parking lot nearby when he walked to the University Memorial Center – described as the nerve center of student life on campus — to get some water. That's when he saw freshman Michael George Knorps holding his neck near the sidewalk in front of the UMC and realized the young man had been slashed.

Holt drew his gun as terrified students looked on, Hopper said. Astin babbled about "the end of the world", stabbed himself about six times in the chest and began counting down as if he was planning to detonate a bomb with a cell phone in his hand.

That's when Boulder police officer John Smith, a 21-year veteran with the department, arrived. He was returning to the intersection of Euclid Avenue and Broadway to do traffic control on his motorcycle when he heard unusual shouting coming from the direction of the UMC.

It was 9:43 a.m.

Two female students walked past him and asked, "Is that real?" as they motioned over their shoulders. They didn't say anything else when Smith asked for more details. Another pair of students told him a student had just been cut.

Once he got to the scene, Smith indicated to Holt, who was standing at the bottom of a set of stairs from Astin, that he had a Taser.

After a few tense moments, Astin dropped the knife but continued making suicidal statements, such as, "Go ahead and kill me" and "Make me do the floppy," Smith said in an interview Monday afternoon at police headquarters. When Astin continued to refuse to follow commands and began walking toward him, Smith fired the Taser at his chest as Astin continued his countdown.

"I remember thinking, "Do I Tase him before he gets to 1? I think I did Tase him before he got to 1."

Still, it took about six people to wrestle Astin to the ground and get his hands behind his back, Smith said.

He was transported for medical treatment and listed in serious condition at Boulder Community Hospital. Witnesses attended to Knorps, who was laying on a bench, until paramedics arrived.

The finance major underwent surgery Monday afternoon to repair tissue and muscle damage. He was conscious and talking as he went into the operating room and was expected to fully recover. His parents were en route from Illinois to Colorado.

Chancellor G.P. "Bud" Peterson said he talked to Knorps before surgery and when told the chancellor wanted to talk to him, Knorps quipped, "Who's the chancellor" or "What's the chancellor?"

"He seemed to be in good spirits," Peterson said.

His, parents, though remained concerned.

"They want to know how this could happen," Peterson said. "They're very concerned for their son, for his safety and his health."

School officials said Knorps, who lives in Darley Towers at Williams Village, was expected to be released to relatives in Boulder and able to attend classes today.

Knorps is the sixth of seven children in a tight-knit family. Knorps chose the CU in part because his older sister and brother live in Boulder, said Knorps' uncle, Leon Knorps, of Naperville, Ill. He described his nephew as an active and athletic young man who played basketball in high school. Knorps also said his nephew was "a real smart kid" who had a variety of colleges from which to choose.

Rocky Mountain News staff writers Rosa Ramirez, Justin Coons and Erika Gonzalez contributed to this report.