Night had fallen in the sprawling house on Channel Drive in the affluent west metro enclave of Greenwood, just a short walk from Lake Minnetonka.
Brian Scott Short, the 45-year-old homeowner, grabbed a shotgun and headed to the bedrooms of his 17-year-old son, Cole, and his 15- and 14-year-old daughters, Madison and Brooklyn.
He walked into the first bedroom, aimed the gun at the sleeping child and pulled the trigger, sources with direct knowledge of the investigation told the Star Tribune on Friday.
Short then did the same to his other two children.
Startled by the noise, Short's 48-year-old wife, Karen, grabbed a cellphone to call 911. But Brian tracked her down in another bedroom and shot her dead. She, like the children, was shot in the head.
Short then went into the home's attached garage and turned the shotgun on himself.
South Lake Minnetonka interim Police Chief Mike Siitari confirmed Friday at a news conference that a shotgun was found in the house, though he would not say where.
On Saturday afternoon, investigators estimated that the deaths occurred late Monday night or early Tuesday morning and said they had not determined a motive in the killings. Earlier in the day, the Hennepin County Medical Examiner's office released confirmation of the family members' names and causes of death. Each died of a shotgun wound to the head.