A 45-year-old man killed eight people, including a pregnant woman and two young children, at a home in Erie, Pennsylvania, before taking his own life, police said Saturday.

Erie Police Chief Rick Lorah said seven of the victims were related to the gunman, while the eighth was a friend of the pregnant woman. The shooting occurred on Friday.

Investigators recovered video and audio evidence indicating muffled gunshots came from inside the house shortly before two distressed women arrived and knocked on the door shortly before 5pm. The gunman then came outside and shot the women as they ran towards him before returning inside, Lorah said.

Police found the two women dead outside the house. After deploying a drone and a robot, officers entered the building and recovered the bodies of a 5-year-old boy and a 1-year-old girl on the first floor, two women and two young men in a stairwell, and the gunman on the second floor.

Lorah declined to discuss the motive, saying investigators would interview relatives and examine the cellphones of the women killed outside the house.

Police arrived within minutes of receiving an alert from ShotSpotter, a gunshot detection system that uses microphones and artificial intelligence to identify gunfire. No further shots were fired after officers arrived, he said.

Pennsylvania Governor Josh Shapiro offered his administration’s support to Erie Mayor Daria Devlin and the victims’ families. District Attorney Elizabeth Hirz urged the public not to spread rumours or unverified information while the investigation continues.

Shapiro later described the killings, along with the shooting of two Philadelphia police officers early Saturday, as a dark day for the state.

Erie is located about 190 kilometres north of Pittsburgh.