A 4-year-old Virginia boy was mauled to death by an American bully dog while his horrified older brother helplessly watched, according to police and his devastated family.

Little Garcia Welch, who had just started preschool, was attacked Sunday while spending the weekend with his dad in Louisa County — and police had to “put down” the canine while it was still biting him, according to the county sheriff’s office.

Responders rushed the boy to a landing area to be airlifted to a hospital, but he was declared dead before he was loaded onto the helicopter, according to cops.

“He was a beautiful kid,” Garcia’s aunt, Cynthia Russ, told WVIR. “He was fun and sweet and kind and he made friends everywhere. And he just, he didn’t deserve this.

“He just had so much ahead of him and we were just excited to see it.”

Police did not say who owned the dog nor if there were adults present at the time of the attack, alarming locals, according to CBS19 News.

But Garcia’s traumatized older brother Gabriel was there and desperately “tried to stop it,” the aunt said.

“I talked to my nephew that night and he was just crying and he was screaming,” Russ recalled.

Cathleen Russ, Garcia’s mother, said her son was spending the weekend with his father, from whom she had recently separated.

Garcia loved music and playing video games with his older brother, Russ said.  

He had also just started preschool at Thomas Jefferson Elementary School. 

Principal Jesse Cleaver said in a letter to the school community that although the young boy “was just beginning his time at Thomas Jefferson Elementary School, he quickly made a meaningful impression on those around him with his kind, friendly, and respectful personality.”

The dog attack remains under investigation.

The Louisa County Sheriff’s Office did not immediately respond to The Post’s request for more information.