The Maine State Police at the apartment complex where the family was found. (Robert F. Bukaty/AP)

The deaths of five people — all family members, including three young children — in a Maine apartment over the weekend came at the hands of a member of the family, authorities confirmed Monday.

Police called the quadruple murder-suicide “one of the worst cases of domestic violence in Maine’s history” in a statement Monday, outlining a graphic and brutal sequence of events that unfolded in the apartment complex in southern Maine.

Joel Smith, 33, shot his family to death  Saturday night  about 11:30 p.m., the Maine State Police said.

According to police, Smith, using a 12-gauge shotgun, shot the two older children — Jason Montez, 12, and Noah Montez, 7 — inside their respective bedrooms. He shot and killed his wife, Heather Smith, 35, and their daughter, Lily Smith, 4, inside his and Heather’s bedroom. Smith then took his own life. His body and the gun he used were found on the floor next to his wife and daughter, police said Monday afternoon.

Police had initially said that it appeared that a member of the family was responsible for the shooting, which occurred inside a second-story apartment in the Riverview Apartment Complex in the city of Saco.

Heather Smith had told a family friend  Saturday night that her husband had threatened suicide earlier in the week, pointing a gun at his head, but it does not appear that anyone sought any help after that incident, according to police.

Authorities did not find a suicide note.

A neighbor told the Portland Press Herald that the family was grilling dinner outside their apartment  Saturday night and that it did not appear that the adults were arguing or angry.

Police said that this is the sixth time since 1941 that four people were killed in a homicide in the state.

The grisly scene was discovered  Sunday after a family friend contacted the apartment complex and asked a maintenance worker to check on the family.

Joel Smith was a maintenance worker at the complex, and he and his family moved to the state from Arizona in recent years, police said.

Saco, home to about 18,000 people, is  25 minutes south of Portland.