Four people were killed Sunday evening in a Pittsburgh suburb in what police believe was a triple murder-suicide.

Officers and homicide detectives were at a home on a dead-end road of about 10 houses in Shaler, where they believed a man shot his wife and two daughters before killing himself.

All were found dead inside the home, Shaler police said.

Police Chief Jeff Gally could not release the names of the victims, but said the family had only lived in the rented home a few weeks. He believed they may have moved to the neighborhood from Ross.

According to the chief, an older daughter, aged 8 or 9 years, was found in a hallway of the home, while the mother and an infant girl were found on the bed inside the master bedroom.

The father was also found in the master bedroom near a closet.

All four victims were shot in the head. The weapon was a .357-caliber handgun, Gally said.

The mother and older girl were dressed in night clothes, the chief said. The man, who has no criminal record in Allegheny County, was dressed in street clothing.

Neighbors called 911 and reported hearing shots fired in the home about 10:30 p.m.

Jess Larkin, who lives one street away from the shooting scene, said she heard gunshots and later spoke with a friend from the neigborhood who told her she had heard a loud argument in the home, followed by shots and then only silence.

"We have no indication as to what caused this tragedy," Gally said.