Story highlights The officer called 911 to say he had killed his wife and son

His home was burning when the SWAT team arrived

After the fire was put out officers found three bodies in the home

Survey: Last year, 126 police officer killed themselves

Even for stone-faced, seen-it-all-before officers, the act that took place at a police lieutenant's Las Vegas-area home Monday was deeply distressing.

The 52-year-old lawman, police said, killed his wife and child, called 911 to say he was burning his house down and warned he would take the life of anyone who tried to stop him.

Then he waited.

When a SWAT team arrived at the lieutenant's Boulder City home, they found Hans Pieter Walters outside with what looked like a handgun.

Officers asked him to drop the weapon -- commands the lieutenant must have screamed many times before in his 20-year career. He ignored them and ducked back into the blazing home.

It was then, police believe, that he killed himself.

Once firefighters put out the blaze that tore through the home, they found Walters's body, his 46-year-old wife's, and their five-year-old son's.

The lieutenant worked for the Las Vegas Metropolitan Police Department, where he supervised patrol officers, CNN affiliate KVVU reported.

The station had interviewed him before about other crimes.

The wife, Kathryn, worked for some time as a Las Vegas police officer, the Las Vegas Review-Journal said.

She won a community service award and a lifesaving award before leaving the department in 2004.

"Anyone involved with law enforcement for any amount of time is usually prepared for any scenario, but nobody can prepare for something like this," Las Vegas Metro Sheriff Doug Gillespie told reporters.

Last year, 126 police officers killed themselves, according to the National Study of Police Suicides by the nonprofit The Badge of Life.

It's a steep drop from the other two years the survey was conducted: 143 in 2009 and 141 in 2008.

Yet, it's cause for concern.

"In spite of this encouraging news, the fact is that police suicides continue at a rate much higher than the number of police officers killed by felons," the group said.

Folks who knew Walters were also trying to make sense of it. The soul-searching was agonizing for some.

Retired Las Vegas lieutenant Randy Sutton told KVVU he had worked alongside Walters for years.

"There's no rhyme or reason," Sutton said, saying the lieutenant was hard-working and seemed well-adjusted.

This is "the most unconscionable, dishonorable thing to do I can ever imagine," he added.

"The memories I have of him, they mean nothing to me anymore."