A Rockaway Township doctor was shot and killed by his son Wednesday when he made a surprise visit to his Pennsylvania apartment, said authorities.

As he fled the scene, the gunman shot and wounded a 12-year-old boy on a scooter who "creeped" him out, according to the Montgomery County Prosecutor's Office in Pennsylvania.

Charged with first degree murder, Steven Mark Quadrel, 24, told police he emptied "four or five clips" from his pistol at his father, Dr. Mark Quadrel, inside his Norristown, Pennsylvania, apartment where the two argued, according to prosecutors.

Mark Quadrel, 58, was a resident of Rockaway Township and an internist at Internal Medicine Of Morris County in Mine Hill. Steven Mark Quadrel, who is a former Rockaway Township resident, told investigators his father arrived unannounced at his apartment Wednesday afternoon, and their conversation turned into an argument.

Steven Mark Quadrel, according to police, said he went to his truck to retrieve his semi-automatic 9 mm Beretta equipped with a laser sight. He returned to the apartment, where he loaded the weapon and began to shoot his father in the back and head as he fell, the affidavit states.

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As the suspect fled his apartment, he told police he encountered a 12-year-old boy on a scooter, fired one round at him and continued to flee, records show. The boy was grazed on the top of his left hand and treated at a nearby hospital.

The boy told police he saw a white man with a short beard run past him, then moments later run back toward him. The man pointed a gun with a red beam aimed at the boy's face, lowered the gun and shot at him, according to the affidavit.

The boy ran off before he realized he had been wounded, records show.

Investigators said Steven Mark Quadrel told them the sight of the boy "creeped" him out, so he shot him. He was arrested later that afternoon when police responded to a call of gunfire on Sandy Street. After they interviewed the suspect, police went to his apartment, where they found the door ajar and Mark Quadrel's body lying face-down on the floor.

The Montgomery County Coroner’s Office autopsy determined the doctor's cause of death was gunshot wounds to the head and torso.

Police found 23 cartridge casings and eight projectiles at the scene, records show.

Steven Mark Quadrel was remanded to the Montgomery County Correctional Facility. A preliminary hearing is scheduled for Nov. 9.

In addition to the first-degree murder charge, he is charged with aggravated assault, possession of an instrument of crime and recklessly endangering another person.

Anyone with information concerning the homicide is asked to call the Norristown Police Department at 610-270-0977 or the Montgomery County Detective Bureau at 610-278-3368.

Staff Writer William Westhoven: 973-917-9242; wwesthoven@Dailyrecord.com.