A man fatally shot eight people, including a pregnant woman and children, at a Pennsylvania residence on Friday before killing himself, police say.

The victims have not been publicly identified, but seven relatives and a family friend died in the rampage.

At a Saturday news conference, Erie’s police chief, Rick Lorah, said it was premature to speculate about the suspected gunman’s motive but noted mental health may have played a role.

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Police discovered the killings about 5pm Friday when officers were called to a residence following reports of gunfire. Witnesses told authorities that they had seen an attacker with a gun outside the property before making his way inside.

Responding officers discovered two women lying dead in the street, both having suffered gunshot wounds. Inside the home, police said they made a devastating discovery, finding six additional victims, including a five-year-old boy and a one-year-old girl, as well as the suspected assailant. Investigators believe the attacker died from a self-inflicted gunshot wound.

Video footage showed the women arriving in distress at the residence. They paced outside, pounded on the door and tried to alert neighbors.

Authorities believe the suspected shooter came out of the residence, exchanged words with the women and then fired at them.

“They knew something was going on at that house. We have to figure out what that is,” Lorah said on Saturday.

The suspect had a history with law enforcement, but its nature remains unclear.

At the news conference, Erie officials also addressed criticism that they were slow to share details of the shooting with the public.

Some of the family members who also lived at the residence had been away, according to Erie’s mayor, Daria Devlin.

“We could not allow this to be received on the news, numbers of people, before we had the opportunity to speak with them,” she said.

Lorah previously spoke about the scale of the mass shooting, describing the scene as among the most distressing and heartbreaking he had witnessed.

“The loss of life is devastating and the circumstances we are working through are deeply disturbing,” Lorah said.

He added: “Our hearts are with the victims, their families and everyone affected by this tragedy. There are no words that can adequately express the magnitude of the loss of life here.”

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Figures from the Gun Violence Archive indicate that the killings in Erie marked at least the 19th mass murder of the year. Such cases are defined as ones in which four or more victims are murdered.

Many of those mass murders have been what are considered family annihilations, in which an attacker kills multiple close family members.

The nonpartisan archive also indicated that the killings in Erie were among more than 500 mass shootings across the US since the beginning of January. Mass shootings are defined as cases in which four or more victims are shot whether fatally or non-fatally.

Mass shootings for years have remained a persistent problem in the US, often intensifying public demands for stronger gun control measures at the federal level.

Despite those calls, Congress has not enacted such restrictions sought over the years.

• In the US, you can call or text the 988 Suicide & Crisis Lifeline at 988 or chat at 988lifeline.org. In the UK and Ireland, Samaritans can be contacted on freephone 116 123. In Australia, the crisis support service Lifeline is 13 11 14. Other international helplines can be found at befrienders.org