The constable went to the apartment near Duncannon, about 10 miles northwest of Harrisburg, at about 10 a.m. Monday to enforce a district judge's eviction order, state police said Tuesday.
A man answered the door, closed it, then reopened it and exchanged words briefly with the constable, police said. He then pointed a loaded .223-caliber rifle that had been "slung and concealed along his body" at the constable's chest, police said. Ciara Meyer was standing behind her father, authorities said.
The constable, investigators said, drew his own .40-caliber weapon and fired once, but the bullet went through the man's upper left arm and hit the girl. She was pronounced dead at the scene.
State police said the suspect's rifle was found "with a loaded chamber and a magazine containing 30 rounds."
In Pennsylvania, constables are elected officials with limited law enforcement powers. They serve warrants, transport prisoners and perform other duties for Pennsylvania's district courts, the lowest level of the judiciary.
The man being evicted, Donald Meyer, 57, was flown to Hershey Medical Center for treatment. He is charged with aggravated and simple assault, terroristic threats, and recklessly endangering another person. A phone listed in his name wasn't working Tuesday and court documents don't list an attorney who could respond to the accusations.
Apartment complex employees were at the scene to assist with and witness the eviction and provided statements to investigators, police said.
The Susquenita School District, while not commenting on whether the girl was a student in the district, said psychologists and guidance counselors were working with counselors to provided support to students and staff.
Information from The Associated Press was used in this post.