WOODBRIDGE (CBS13) – A man was badly injured after opening the door to his MMA-trained teenage neighbor who then severely beat the man, according to authorities.

On Monday, just after 7:30 p.m., a man says he heard a knock on the door. After seeing that it was his neighbor, he opened the door and that’s when he was suddenly attacked — with no explanation, according to the San Joaquin County Sheriff’s Office.

Surveillance video caught 19-year-old Juan Ramirez punching and kicking the man, then hitting him across the face with baseball-sized rocks. Ramirez then allegedly dragged the man across his property.

The victim was subsequently taken to the hospital where he was treated for abrasions on the top and back of his head, cuts and bruises throughout his body, broken ribs, a collapsed lung, and a ruptured eardrum. He was also examined for a possible broken jaw and a broken wrist.

Ramirez, who claims he has MMA training, was booked into the San Joaquin County Jail on charges of assault with a deadly weapon, felony battery, and mayhem.