(ANNAPOLIS, Md.) -- An electrical failure that set ablaze a 15-foot Christmas tree caused a mansion fire in Annapolis, Maryland, earlier this month that killed six people, authorities announced Wednesday.
Bureau of Alcohol, Tobacco, Firearms and Explosives agents also concluded that the fire, which started in the home's great room, was an accident.
"While the explanation that has been shared with us today does not bring solace, it does start us down the long road to acceptance," read a statement issued Wednesday by the Boone and Pyle families.
It took almost a week for six bodies to be found in the burned-down mansion. All those who were thought to be inside are believed to be accounted for, according to fire department officials.
The 16,000-square-foot mansion was owned by tech executive Don Pyle and his wife Sandra.
According to relatives, the Pyles had four of their grandchildren -- Alexis (Lexi) Boone, 8; Kaitlyn (Katie) Boone, 7; Charlotte Boone, 8; and Wesley (Wes) Boone, 6 -– over at the time of the four-alarm fire. All six died in the blaze.
Crews started going through the wreckage last Wednesday, according to ABC affiliate WJLA, a process that ATF investigators said could take weeks.
The house was "built more like a commercial structure," Anne Arundel County Fire Capt. Russ Davies told reporters, so searching is a "time-consuming process."
Initially the fire had been handled as a criminal investigation.
Relatives described the Pyles as loving grandparents nicknamed “Pop-Pop” and “Dee-Dee.” The night before the blaze, Don and Sandra treated their four grandchildren to a special outing to Medieval Times, according to a family spokeswoman -– even taking them to Target beforehand to pick up costumes for the occasion.
Family members of the victims thanked well-wishers last week in a statement. Attributed to "the Boone and Pyle families," it said in part, “We wish to express our gratitude and appreciation for the love and support being shared with us during this tragic event. We are blessed that so many family, friends, and neighbors have come together for us in our time of need."
“Life is fragile," the statement concluded. "Make time today to embrace your loved ones."
Authorities said at Wednesday's news conference that they would conduct additional tests and analysis.
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