A member of the family called 911 regarding a “medical emergency” at 135 Center Ave. in Abington, Plymouth County, around 7:30 a.m. on Monday, District Attorney Tim Cruz said during a news conference.
The relative had gone to the house to help get the three children to school, he said.
“This is just a horrible, horrible event here for the town of Abington and for the children and the schools,” Cruz said.
Cruz did not say how the family member was related to the victims.
“The person found an individual bleeding, laying in a position on the couch in the downstairs area and they called the police,” he said.
Police and emergency services first found the body of a 40-year-old woman and the bodies of the three children — girl and boy twins and the 11-year-old. They then found the body of a 43-year-old man.
The victims were confirmed to be members of the same family, Cruz said. Their identities have not been released because other family and next-of-kin have yet to be notifed about the deaths, he said.
“This appears to be an isolated incident,” Cruz said.
Authorities said they were not aware of any ongoing domestic issues in the home.
“There was no indication whatsoever and no previous calls that would certainly indicate any type of an issue going on at that household,” Abington Police Chief David Majenski said during the news conference.
The deaths were all a result of gunshot wounds, according to a preliminary investigation, he said. A medical examiner would determine the official manner and cause of death. Cruz said he expected police to find the weapon or weapons involved.
“This is an incredibly terrible event. … It’s a crime. … A crime occurred in that building and three little children are gone forever as a result of this,” he said. “There’s not a lot of answers to a heck of a lot of questions.”
Massachusetts State Police were reportedly helping Abington police in the active and ongoing investigation.