The call came in around 8 p.m. for a shooting on the 2900 block of Reifsnyder Road in the Gilbertsville section of New Hanover Township.
According to the Montgomery County District Attorney's Office, an adult son and his wife were murdered by his father, who then killed himself.
When officers arrived Monday night, police found Rebecca Evans, 51, dead at the scene. Stephen Mihalcik, 56, was taken to Reading Hospital, where he later died of his injuries.
Gerald E. Mihalcik, 78, was found at the scene, dead of an apparent self-inflicted gunshot wound, officials said.
"This is such a tragedy and my heart goes out to the surviving family members," said District Attorney Kevin Steele. "We are seeing more domestic violence homicides in Montgomery County this year than ever before. If you are living in a violent situation at home, please call for help. Police are ready to respond through 911."
The Laurel House hotline at 800-642-3150 or the Women's Center of Montgomery County hotline at 800-773-2424 can also be used, Steele said.