"I think that was a front for him," Julius Windham said as he stood at a memorial to victims of Friday's shooting in the city of Erie, including his one-year-old daughter Amarianna, her pregnant mother and the woman's five-year-old son and unborn baby.
"Him every day, him smiling and being just - you would think of nothing like that would happen," Windham said.
The 45-year-old gunman took his own life. Erie Police Chief Rick Lorah said he was related to seven of the victims. The eighth was a friend of the pregnant woman, he said.
Those killed include two women outside the home
Mourners on Sunday placed candles, flowers and stuffed animals outside the home where the man opened fire.
Windham wore a T-shirt with pictures of the slain woman and children and the words, "Forever In My Heart".
"Words can't even explain what I'm going through right now," Windham said.
Video and audio evidence recovered by investigators included muffled gunshot sounds coming from inside the home just before two "distressed" women arrived and began pounding on the door, Lorah said.
The gunman then came out and shot them as they ran toward him, before returning inside.
Responding officers found the two women dead outside.
After deploying a drone and robot, they went inside and found the bodies of the five-year-old boy and one-year-old girl on the first floor; two more women and two young men in a stairwell; and the shooter on the second floor.
Lorah declined to discuss motive but suggested mental health could be a factor. He said investigators would talk to relatives and examine the mobile phones of the women who were killed outside the home.
"They knew something was going on at that house," Lorah said. "We have to figure out what that is."
Nicole and Debra Eller, whose best friend was among the victims, said they've known the family for more than 30 years. Nicole Eller said the shooter "was a good guy, and then he started going downhill with everything".
"They were a lovely family. Who would have thought this would ever happen?" Debra Eller said.
1800 RESPECT (1800 737 732)
Lifeline 13 11 14
Men's Referral Service 1300 766 491
