Klementovich, a 42-year-old Army veteran, ultimately surrendered and was charged with 85 counts of attempted homicide, aggravated assault, recklessly endangering another person, assault on police officers, and possessing an instrument of crime.
He was being held Monday on $1 million bail, with the condition that he undergo a mental-health assessment before being released.
"He was having a bad time psychologically," Bucks County District Attorney David Heckler said. "There was some mention that he was on disability at work, and that medication was involved."
A spokesman for the Clifton (N.J.) Police Department said Klementovich had recently returned after being out for an injury unrelated to work.
Klementovich, in the e-mail to his ex-wife, said he was taking steroids, according to court documents. He apologized to her for his shortcomings.
The couple, who has two children, went through a bitter divorce, authorities said, with Klementovich moving out of the two-story brick house on Bittersweet Drive. On Father's Day, he arranged a family get-together elsewhere, but instead returned to the empty house and reported a "civil dispute" to police, authorities said.
Police found a note in the driveway saying Klementovich was armed with "scoped rifles, 200 rounds of ammunition, he was law enforcement and that he was ready to die," according to court documents.
As neighbors were told to evacuate the area, officers and their police cars were shot at, with one officer suffering a minor wound from shrapnel, police said.
Officers from neighboring towns and a regional SWAT team responded, their cars, vans, and an armored Bearcat filling the tree-lined street. They came under fire several times during the afternoon, with only a few vehicles getting hit.
Officers from Klementovich's department in Passaic County also responded, helping to talk him into surrendering, the department said in a statement.
Klementovich has "received numerous commendations" during his 15 years in the patrol division, the statement said.
His former supervisor, retired Lt. Patrick Ciser, called Klementovich "one of my best officers" and said he served as a training officer for rookies.
Ciser said he was grateful for the restraint the responding officers used during the long standoff.
"As good as he is — a marksman, physically fit, a combat veteran — the SWAT team and all the men there could have taken him out," Ciser said. "They were kind enough to show patience and professionalism. They saved that man's life."
"I hope that he gets the help he needs," Ciser added.
Hours after Klementovich surrendered on the front lawn, residents of the Doylestown Lea development strolled the sidewalks and clustered in driveways, swapping stories.
"We weren't sure whether he was out and about in the neighborhood or confined to his house," said Lisa Gervais, who hunkered down in her house with her husband and 14-year-old son the entire time.
"We kept hearing gunfire — first I thought it was fireworks," Gervais said. "At 5 o'clock, we heard six shots." Then police called and said Klementovich was in his house, "and we were calmer after that,"
The family went to bed at 11 p.m., with police still stationed outside. Gervais knew the standoff was over a short time later, "because I heard cars going by on the street. In this development, you could hear a pin drop from 2 p.m. to midnight."
Contact Bill Reed at 215-801-2964 or firstname.lastname@example.org, or follow on Twitter @breedbucks. Read his blog, "BucksInq," at www.philly.com/bucksinq.
Inquirer staff writer Edward Colimore contributed to this article.