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A Marine Iraq War veteran who police say killed his ex-wife and five of her relatives in a multi-town shooting spree outside Philadelphia took his own life, authorities said Tuesday, ending a more than daylong, two-county manhunt.

Bradley William Stone, 35, was found in a wooded area in New Hanover Township, about a half mile from his home in Pennsburg, Montgomery County District Attorney Risa Vetri Ferman said at an afternoon news conference.

She said that Stone was believed to have died "from self-inflicted cutting wounds in the center part of his body." She did not know how long he had been dead when he was discovered shortly after 1:30 p.m.

Ferman said a motive was not immediately clear, but said the killings came after a recent custody dispute between Stone and his ex-wife Nicole over their two children.

"There is no excuse. There is no valid explanation. There is no justification for snuffing out these six innocent lives," Ferman said. "This is just a horrific tragedy that our community has had to endure, and we're really numbed by what we've had to go through the past couple of days."

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    The rampage began around 3:30 a.m. on Monday, when Stone shot and killed Patricia Flick, the sister of his ex-wife, Nicole Stone, at her home in Souderton, also killing Flick's husband, Aaron Flick, and her 14-year-old daughter, Nina Flick.

    Her 17-year-old son, Anthony Flick, suffered "significant" cutting injuries to his head and hands after apparently defending himself from Stone, Ferman said, adding that she believed reports that Anthony had had three of his fingers cut off were accurate. He was being treated at a Philadelphia hospital and was in serious condition.

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    Nicole Stone's mother, Joanne Hill, and grandmother Patricia Hill were killed next at their home in nearby Lansdale. Investigators were alerted by a hang-up call to emergency dispatchers, Ferman said.

    Then, around 5 a.m., Stone went to Nicole Stone's apartment, located in the Harleysville section of Lower Salford Township, investigators said. Stone broke in through a glass door, shot and killed Nicole Stone, and fled with their two children, the woman's neighbors said. Authorities said Stone then delivered the two children, who were unharmed, to a neighbor in Pennsburg. Stone's current wife and infant child were safe and secure as well, she added.

    All three towns are within a few minutes of each other. Pennsburg is located 48 miles northwest of Philadelphia.

    "We live here in a very peaceful community," Ferman said. "To have an event like this shatter the peace and tranquility here is really disturbing."

    She said one firearm, the model of which she did not specify, had been recovered at the scene of Nicole Stone's home, and a Beretta was missing, though she said it was possible it could still be with his body, which hadn't been moved as of 4 p.m. so as to preserve the scene for the coroner.

    The hunt for Stone had spread to two Pennsylvania counties as authorities urged residents to be "vigilant and cautious," warning that Stone was armed and dangerous.

    Some schools were closed Tuesday, hospitals and other public places increased security and residents remained on heightened alert, even as officials lifted a shelter-in-place order for parts of Bucks County, where a knife-wielding, fatigue-clad man resembling Stone attempted a carjacking in Doylestown on Monday night. But there was no immediate confirmation that the suspect was Stone.

    Authorities had recovered Stone's cellphone, but Ferman said no meaningful information had been recovered from it.

    Friends of the family were shocked to hear of the rampage.

    "(Nicole Stone) would tell anybody who would listen that he was going to kill her, and that she was really afraid for her life," said Evan Weron, a neighbor of Stone's ex-wife, Nicole Stone.

    "Everything started being blocked off, the SWAT was then later called in, then we had the tanks pull up," said Don Smith, describing the scene near his Souderton home.

    Brad and Nicole Stone, 33, married in 2004 and filed for divorce in March 2009, according to court records.

    The former couple recently sparred over custody of their two children, with Brad Stone filing an emergency petition Dec. 5 and Nicole Stone responding with a counterclaim Dec. 9, according to court records. The outcome of their dispute was not clear.

    Nicole Stone's neighbors at the Pheasant Run Apartments in Harleysville said they were awakened Monday morning by the sounds of breaking glass and gunshots.

    Weron said Nicole Stone would talk frequently about the custody dispute.

    "(Nicole) came into the house a few times, a few separate occasions, crying about how it was very upsetting to her," Weron said.

    Stone served in Iraq and held the rank of sergeant at the time of his discharge in 2008, U.S. Marine Corps records show.

    Fox News' Justin Fishel, Rick Leventhal and The Associated Press contributed to this report.