The knife had a five-inch fixed blade with an overall length of 10 inches, according to a news release issued Wednesday night by Montgomery County District Attorney Risa Vetri Ferman and Towamencin Township Police Chief Paul T. Dickinson.
The father was cooperating with the township and county investigation and was being treated at a hospital for injuries from the attack, Ferman and Dickinson said.
Towamencin police had been called twice before to the house, in the 100 block of Oxford Road, they said.
On April 30, police were called because the teen was enraged, they said. He reportedly had made vague threats in the past to harm himself.
Ferman and Dickinson said the tension in the household had subsided, but police were called back May 26, when the boy threatened to kill himself.
Stephen Schmitz was involuntarily committed that day to the Horsham Clinic, Ferman and Dickinson said. He was released Tuesday.
Detectives continued to process the shooting scene and conduct interviews Wednesday night. They asked that anyone with information about the behavior of the teen, including threats he may have made, call the Montgomery County Detective Bureau at 610-278-3368 or Towamencin Township police at 215-368-7600.
Investigators cordoned off the property with yellow police tape and erected a blue tarp near the side of the house. About 5:30 p.m., a county coroner's van arrived.
A half-dozen teens clutching cellphones stood solemnly at one end of the barricaded street Wednesday night. None wanted to comment.
Eric Schmitz has owned the property since 1993, records show. He is listed on the Hatfield Police Department's website as its "right to know" officer and the lieutenant of administration, "responsible for the internal police department function."
Hatfield Township Manager Andrew Haines, who had apparently left for the day and rushed back to the township building, said: "We have no comment at this point until we ourselves learn more."
Tom Zipfel, president of the five-member Hatfield Township Board of Commissioners, said he had known Eric Schmitz for about five years.
"He's a wonderful police officer, there is no doubt about that," Zipfel said. "He has served us fantastically for many years. . . . You couldn't find a more decent man or a more decent police officer."
Zipfel said he did not know enough about the shooting to comment, but added: "Our township as a whole is thinking about him and his family."
Contact staff writer Kathleen Brady Shea at 610-696-3815, kbrady@phillynews.com, or @brandywinebits on Twitter. Read her blog, "Chester County Inbox," at www.philly.com/chescoinbox
