Apparently, this could have been an awful day in Salt Lake City.

We wish we had some greater truth to glean or some political solution to propose, but there is only gratitude. If a crisis worker hadn’t reported odd behavior to police, the unthinkable might have happened here, again.

This week, people along the Wasatch Front learned about what probably are the most effective tools to thwart mass murder — vigilance and a willingness to report suspicious activity. Laws are important, but nothing beats person-to-person concern and observation.

Not many details are available, except that a crisis worker at Pioneer Valley Hospital decided to ignore confidentiality rules on Aug. 12 and contact West Valley Police after learning that Jack Harry Stiles was allegedly planning, in great detail, to kill as many people as possible in Salt Lake City on Sept. 25.

Police investigated and determined there was good reason to take the threat seriously. Stiles, the world learned Tuesday, has now been charged with threat of terrorism, which is a second-degree felony, and had bail set at $1 million.

He reportedly did not even possess a gun at the time of his arrest, but charging documents said he had made detailed plans for carrying out a mass murder after planning to obtain two automatic handguns, five extra magazines and explosives. Specifically, he planned to attack the City Creek Center during lunch and kill as many people as possible. He also planned to shoot up a movie theater in Sugar House and detonate a bomb beneath a UTA bus or TRAX train.

He had studied escape routes, hiding spots and how to make a bomb, authorities said.

The ability to do all those things without being stopped seems far-fetched, but not much more so than what Anders Behring Breivik did in 2011, when he detonated bombs in government buildings in downtown Oslo, Norway, and then traveled to an island where he murdered several young people at a camp.

If Stiles accomplished even a small portion of his alleged plot, the results would have been awful. Utahns have learned the hard way, most notably through such a shooting at Trolley Square in 2007, how lives and families can be forever changed by such crimes.

People search for motives in order to understand such crimes. In this case, all that has been made public is some connection between Stiles’ plot and the one-year anniversary of his mother’s death.

Certainly, more can be done to provide mental health services where needed, but even that is no guarantee against such behavior.

The unnamed crisis worker’s vigilance comes one month after school worker Antoinette Tuff came face to face with a gunman at a school in an Atlanta suburb and was able to calm him down and talk him into giving himself up without harming anyone.

Both people are heroes who likely saved many lives.

Absent any greater understanding as to why such unthinkable crimes keep appealing to the odd few, human interaction, sympathy and concern for the safety of everyone is the best defense.