A two-decade family feud came to a bloody and deadly end Friday when estranged daughter Josephine Ruckinger and her husband murdered her mother and brother before her father killed the couple, not knowing it was his daughter who committed the crimes.

The chaotic scene started around 10 a.m. Friday, when Ruckinger and her husband, Jeffrey, both 43, rang the front door of the home of Josephine’s family in Allegheny Township, Pa., and opened fire, WTAJ reported. Josephine Ruckinger killed her mother, Roberta Frew, 64, while husband Jeffrey Ruckinger murdered her brother, 47-year-old John Frew, Jr. Josephine’s father, John Frew Sr., then shot and killed the Ruckingers.

The Pennsylvania State Police said their investigation discovered that the elder Frew did not realize it was his estranged daughter and her husband who killed his family until he killed the couple.

"What we are lead to believe, at this point, [is that] he had no idea that was his daughter until after the fact, after everything unfolded,” Pennsylvania State Trooper John Matchik Jr. told WTAJ.

Josephine Ruckinger was estranged from her family for 20 years, family members told the Pittsburgh Tribune-Review.

Cambria County District Attorney Kelly Callihan said the incident “was a home invasion that was a murder plot. [The Ruckingers] came armed and ready to commit murder.”

"Clearly, these two individuals came to this house to carry out a plan, a deadly attack on this family,” she added.

The Tribune-Review said the couple had a 12-gauge shotgun and pistols when they opened fire on the Frew home.

Matchik said the elder Frew “has been very cooperative in this particular situation,” adding that authorities have not made any arrests, although the incident is still an ongoing investigation. It’s believed that Frew acted in self-defense.

The trooper described what happened when the Ruckingers rang the Frews’ doorbell.

"Roberta answered the door," he said. "We believe she cried out something to the effect of, 'Oh my God, they have guns.' At this time, gunfire erupted."

Searches of the Ruckingers’ car and the Frew home were conducted. Police said they found a gas can, lighter fluid and a large amount of ammunition in the vehicle, according to WTAJ.

Despite finding those items, authorities would not say whether the Ruckingers attempted to light the house on fire, the Tribune-Review reported.

Law enforcement and the community were shocked over the number of deaths and the circumstances of the Pennsylvania family shooting.

“I have been in the coroner's office since 1980 and we have not had this many deaths, from a homicide, in a single incident,” Cambria County Coroner Dennis Kwiatkoski told the Tribune-Review.

Neighbor Ken Wills told WTAJ, “People will be on their toes for a few years. You just don’t expect it.”