A family of five was found shot to death in a small town outside Boston on Monday morning, authorities said.

Among the dead were twin 9-year-olds — a boy and a girl — and an 11-year-old girl, Plymouth County District Attorney Tim Cruz said.

The children’s mother, 40, and father, 43, were also found inside the condo in the town of Abington, Cruz said. Local police found their bodies after a relative stopped by to take the kids to school, he said.

Authorities did not immediately identify the family and a possible motive behind their deaths remained unclear.

The killings appeared to be an isolated incident and there was no ongoing threat to public safety, Cruz said. He added that authorities were not aware of any “domestic issues” at the home.

NBC Boston reported that the deaths were part of a suspected murder-suicide.

“I think that when something unimaginable like this happens, there are always going to be more questions than there are going to be answers,” he said.

Relatives of the victims released a statement through Cruz’s office saying the family “has suffered an unfathomable loss” and asking for privacy.