Eric Schmitz, 56, is described by peers as a calm, unflappable Hatfield Township police lieutenant, the consummate professional. At home, friends say, he is a loving, devoted husband and parent, a man who never spoke ill of anyone.

His son Stephen, 17, was a North Penn High School junior whose interests ranged from lacrosse to theater. Teachers described him as a bright and caring student.

"They were the ultimate family," said Ed Justice, a longtime friend and former assistant chief of the Montgomery County detectives.

How that family came to be shattered Wednesday in a deadly clash between the father and his mentally troubled son saddens and bewilders many who knew them.

Around 3 p.m., authorities say, Eric Schmitz shot and killed his youngest child in the two-story Towamencin house where Stephen had lived all his life.

"Never in a million years did I think we would be going through this situation," said Hatfield Police Chief Mark Toomey, a friend of Eric Schmitz's since both were hired in 1977.

"It's tough to bring a school of 3,100 to a stunned silence, but that's what happened" Thursday, said Kyle Berger, who taught Stephen Schmitz's seventh-period communications class at North Penn.

Stephen, who struggled with mental-health issues, apparently had attacked his father with a fixed-blade hunting knife soon after getting home from school, authorities said.

An autopsy Thursday afternoon found that the teen died from two gunshot wounds to the body, Montgomery County Coroner Walter I. Hofman said.

District Attorney Risa Vetri Ferman declined to give details Thursday of how the clash occurred or what might have precipitated it. Among other things, she said, detectives were working to obtain the teen's mental-health records.

The shooting happened one day after Stephen Schmitz had been released from the Horsham Clinic, a mental-health facility, after a 13-day involuntary stay. He had been committed May 26, after his father summoned Towamencin police to the family home that afternoon.

Stephen Schmitz had been threatening suicide, Ferman said in a written statement, and his father "prevented [him] from harming himself on this occasion."

Police had been called to the home at least once before, on April 30, when Stephen had become "enraged," Ferman said. But the teen calmed down and his father told police he saw no need for further action.

Many acquaintances said they knew little or nothing of any strife in the home.

Those who were aware of Stephen Schmitz's recent problems were stunned by how they ended.

Katie Berger, an owner of Lansdale's Distelfink Bakery, where Stephen worked two days a week, called him "a wonderful employee. Everyone here loved him dearly."

She had spoken with Eric Schmitz about his son's problems, especially when the young man was at the Horsham Clinic. "He was doing absolutely everything he could to get Stephen help," she said.

Friends said Eric Schmitz and his wife, Lori, a special-education teacher at North Wales Elementary School, seemed ideally suited to deal with a troubled child.

"These are people who should be sculpted on the top of a wedding cake as an example of what we want young professionals and parents to be," said Montgomery County Commissioner Bruce L. Castor Jr., a former county district attorney who knew Eric Schmitz professionally and the couple socially.

"He may be the most calm, easygoing police officer I've ever met," said Justice, a Hatfield sergeant at the time Schmitz was hired. "I've never heard him say one bad word about another person."

Toomey, the police chief who watched his friend rise through the ranks and serve as interim chief in 1992, called Schmitz "extremely honest" and "always the calming influence. Nothing rattled Eric."

Schmitz's version of a rant, Toomey said, was to say, quietly, "I'm frustrated by this."

The Schmitzes worship at Central Schwenkfelder Church, where Lori Schmitz serves on the Christian education board and their children - Stephen and older siblings Drew and Kris - went on summer mission work trips.

Eric Schmitz also has an adult daughter from a previous marriage.

"Lori has the patience of a saint, and she is just as sweet as Eric is nice," said Keith Maurer, a church member who accompanied the boys on a work trip in 2009. "Drew was the more outgoing, jovial, and extroverted one. Stephen was quiet and shy, but always very respectful."

At North Penn, Stephen Schmitz played on the lacrosse team; was a member of the Green Room, a group for students interested in theater; and sang in a select concert choir.

Despite his shy nature, he was a talented singer with a passion for performing, choral director Matt Klenk said.

Principal Burt Hynes said Stephen Schmitz was interested in film and was considering a career as a filmmaker.

School counselors were in the cafeteria Thursday, collecting remembrances and messages for the Schmitz family that students were writing on index cards.

Toward the end of the school day Wednesday, teacher Kyle Berger said, he had met with Stephen Schmitz to discuss finishing his final communications project, a documentary.

"Everything seemed normal," he said. "It doesn't seem possible that it would be the last time I talked to him."

When school let out at 2:22 p.m., Stephen Schmitz walked home, Hynes said, just a couple of blocks from school.

Then, the inexplicable happened.

"You couldn't find a nicer, kinder guy than Eric Schmitz," Ed Justice said. "I pray to God that he finds a way to get over this."

Contact staff writer Larry King

at 215-345-0446, lking@phillynews.com, or @KingInq on Twitter.

Inquirer staff writer Adrienne Lu contributed to this article.