PITTSFIELD — A Sheffield man is believed to have killed his wife and three children Wednesday before setting their house on fire and committing suicide, the Berkshire District Attorney said Thursday. 

Luke Karpinski apparently killed Justine Wilbur and their children — 7-year-old twins Alex and Zoe, and Marek, 3, District Attorney Andrea Harrington said at a news conference at her office in Pittsfield. He then set their Home Road house on fire before killing himself.

Harrington did not disclose a weapon used in the killings or the causes of death. Nor would Harrington say whether the victims were dead before the fire started or how it was set.

"This is a comprehensive and ongoing investigation and we will be limited in the kind of information we can provide," she said.

Meanwhile, state and local authorities continued their investigation Thursday into the deaths. The state fire marshal and other authorities were at the scene on Home Road, and by late morning the road was blocked off to nonresidents. Police said it would remain closed for the rest of the day.

After knocking down the blaze early Wednesday, firefighters found the bodies of Karpinski and Wilbur, both 41, and the couple's three children inside the home. Shock rippled through the small, rural community of about 3,000 people, including at Undermountain Elementary School, which two of the children attended.

"While details are still emerging about the fire, our focus is on supporting our students, teachers, families and community members," Beth Regulbuto, superintendent of the Southern Berkshire Regional School District, said in a statement.

A review of the Sheffield Police Department incident log showed how Wednesday's tragedy unfolded.The first of several calls about the fire came in at 7:48 a.m. Firefighters arrived to find the home engulfed in flames.

At 8:37 a.m., an adult was found dead on the first floor. At 10:33 a.m., three children were found on the second floor.

At the news conference, Harrington confirmed that the mother was found by herself, and the children and father were found together.

At 10:23 a.m., a call came from Karpinski's father, Paul Karpinski, who lives in New Hampshire. A man who answered Paul Karpinski's phone Thursday declined to speak about the incident. Wilbur's sister, Kristen, learned about the fire from Karpinski's family. She then told her mother, who lives in Lanesborough. During the first call, Kristen Wilbur only learned of Luke's death. It wasn't until later that she heard of her sister and the children, she said. 

Chelsea Quenneville, one of the neighbors who called to report the fire, told The Eagle that she and her husband were knocking on the door while the fire was blowing out the windows, and they were concerned about the family's dogs. Karpinski's GMC truck was parked in the garage and Justine's blue Subaru in the driveway.

Another neighbor told The Eagle that when firefighters arrived, they had to move the Subaru out of the middle of the driveway. It was facing the road with the keys inside, said the woman, who asked that her name not be published. 

On Thursday morning, the Subaru was still parked across the street, in a neighbor's driveway.

She noted that Wilbur, who worked as a patent lawyer in Albany, N.Y., worked late on Tuesdays.

"They were very kind people," she said. "And very quiet, private people." The couple's three children caught the bus to the elementary school, which the neighbor's grandchildren also attended.Neighbors had all watched the construction of the home over the past two years, after the couple purchased the land in 2017.

 The couple, graduates of Wahconah Regional High School, had moved back to Massachusetts from Virginia, where they worked in the patent industry. 

Luke Karpinski was a federal chemical patent examiner who worked from home, Kristen Wilbur said.

A statement from the law firm where Justine Wilbur worked says her colleagues are facing "grief and immeasurable sorrow." 

"Justine was a talented attorney who joined our team in 2017 after having built a reputation both domestically and internationally as a patent expert," said the statement from Hoffman Warnick Intellectual Property Law. "Her work was both meaningful and challenging, having encompassed topics ranging from cancer treatment and nanotechnology to advanced materials.

"Justine was smart, knowledgeable, dedicated and hardworking. She was a devoted mother to her wonderful children, and a true friend to everyone in our firm," it said. "We are each devastated by loss and extraordinary sadness, but are comforted and grateful for having shared Justine's infectious spirit and energy."We pray for her family and those who loved her."

There was no indication from Harrington or the family's neighbors in Sheffield about what might have motivated Karpinski to kill his family. Neither Karpinski nor his wife had a record in southern and central Berkshire District Court, and there were no filings related to the couple in Probate and Family Court.

Over the past four years, six Berkshire County women have been killed at the hands of their partners. Five of those killings occurred in Berkshire County, and one in Colorado.