A local lawyer killed his wife and three young children in a murder-suicide that was discovered when firefighters responded to a blaze in their Berkshire County home Wednesday.

Two 41-year-old adults and their children, a set of 7-year-old twins and a 3-year-old, were found dead after firefighters extinguished the blaze at 1343 Home Road in Sheffield, Berkshire District Attorney Andrea Harrington said at a press conference Thursday.

Harrington identified the victims as Justine Wilbur and her husband, Luke Karpinski. She did not release the names of the children. Sources said the children are Alex and Zoe, both 7, and Marek, 3.

“We are investigating this matter as a murder-suicide. At this time, the evidence indicates that Luke Karpinski was the assailant,” Harrington said.

She said Karpinski is a lawyer. The U.S. Department of Commerce listed him as a patent examiner in its Sheffield office in 2017.

Harrington offered her condolences to the relatives of the family.

Firefighters responded to reports of a fire at about 7:50 a.m. Wednesday at the two-story home. After extinguishing the flames, they searched the home and found the victims, she said.

Wilbur was found first and was separate from the rest of the family. Karpinski and three children were found together on the second floor when the search continued, she said.

Karpinski and Wilbur are listed as the owners of the home, which is built on about 5.6 acres of land and valued at $349,300, according to assessor records.

Wilbur is a patent attorney and senior associate at Hoffman Warnick in Albany, New York, according to the law firm’s website. She had a master’s degree in chemistry and previously worked for a pharmaceutical company.

Harrington declined to explain the circumstances of the fire and other details of the murder-suicide because the investigation is continuing. She also declined to say what weapons, if any, were found in the home.

“This is a comprehensive and ongoing investigation,” she said. “Members of the State Police assigned to the Office of the State Fire Marshal and detectives from the State Police Detective Unit assigned to the Berkshire District Attorney’s Office are still combing through the scene and searching for evidence.”

The bodies of the five people were brought to Boston so the Office of the Chief Medical Examiner can conduct autopsies. Officials have not released the cause of death on any of the five, Harrington said.

“The scene is secure and there is no reason to believe that the public is endangered at this time,” she said.

Departments that assisted at the scene of the fire on Wednesday were the Massachusetts State Police Crime Scene Services Section, forensic scientists assigned to the Massachusetts State Police Crime Laboratory, the Massachusetts State Police Collision Analysis and Reconstruction Section, Sheffield and Great Barrington police, and fire department crews from Sheffield, Great Barrington, Monterey, Egremont, Richmond, New Marlborough, Canaan, Connecticut, and Norfolk, Connecticut, she said.