The 12-year-old boy heard a knock at the front door of the Frankford neighborhood home he shared with his grandmother and 10-year-old sister early Sunday morning.

As he approached, before he even opened it, a single bullet blasted through the door, striking him once in the head. He was pronounced dead just after 3 a.m., police said.

“What we know at this time is that there was a knock at the door,” Philadelphia Police Deputy Commissioner Melvin Singleton told 3CBS Philly at the scene. “No descriptions of any persons at the door, one shot was fired. We do have on the porch of the location one 9mm shell casing and that’s all we know at this particular point in time.”

Singleton said he did not believe the boy was the shooter’s intended target. “[The shooter] could not have had any idea of who is on the other side of that front door,” Singleton said.

“It’s a tragic situation,” he told NBC10.

Police and paramedics arrived at the home on the 5000 block of Ditman Street minutes after the 2:45 a.m. shooting. They found the boy bleeding from his mouth and tried unsuccessfully to revive him, police said.

In the darkness, amid the harsh swirl of red and blue police lights, the family’s loved ones converged on the home, where they sobbed and embraced one another on the porch. At the time of the shooting, the boy was home with his grandmother and younger sister, police said.

Police officers and detectives scoured the block and the surrounding area in hopes of finding surveillance video to help them identify the shooter.

The boy’s death marked the 437th homicide in Philadelphia in 2020 — a year in which an inordinate number of the city’s children have died of gun violence.