(CNSNews.com) - While the 1998 shooting at Columbine High School prompted cries for stricter gun control, Monday's shooting at a high school in California is prompting calls for people to be more responsible about reporting students who make threats. California already has some of the nation's most restrictive gun laws.
"People who are looking for a simple answer to this...they're going to be disappointed. There is not going to be a simple, focused answer to why this shooting took place," said Paul Pfingst, the San Diego County District Attorney.
In a television interview Tuesday morning, Pfingst said part of the investigation focuses on "why and whether or not some people should have triggered an investigation that could have prevented this."
Pfingst told NBC's Today show that the information gathered so far is "sobering." He said, "Some of the statements from witnesses indicate that...some people didn't think it [the suspect's threat] was as frivolous" as others have indicated.
"Were there people who were on notice and did nothing? If so, why not? And what can we do to teach kids to come forward and tell their teachers, tell their principals, and so on?"
Pfingst said those questions are top of mind, as investigators start interviewing hundreds of witnesses Tuesday.
Hours after Monday's shooting, California Gov. Gray Davis said, "Every adult and every student should not dismiss any potential warning sign as just a joke."
In a written statement, Education Secretary Rod Paige said, "I urge every parent and every student to listen closely to children who express concern, anger or fear concerning their school, their teachers and their classmates."
Over the weekend, the 15-year-old suspect told a number of people - including one adult - that he intended to shoot up Santana High School in Santee.
"I even mentioned Columbine to him," said Chris Reynolds, whose son was friends with the suspect. "I said, 'I don't want a Columbine here.' But he said, 'No, nothing will happen, I'm just joking.'
"I should've stepped up even if it wasn't true and stuff to take that precaution," said Reynolds in a television interview. "That's going to be haunting me for a long time. It just hurts, because I could've maybe done something about it."
In various interviews, the suspect's friends said they confronted him about the threats he was making, but they backed away when he said he was just joking.
The suspect, described as a scrawny misfit who recently moved to California from Maryland with his father, will be arraigned as an adult on Tuesday on charges of murdering two students and wounding thirteen others.
He apparently took the .22 caliber pistol from home. On Tuesday, the San Diego district attorney said the gun apparently belonged to the boy's father. Police said during the shooting, the suspect stopped to reload as many as four times, firing at least 30 shots.
In Washington, President Bush called the shooting "a disgraceful act of cowardice."