SAXONBURG — A borough man has been arrested on charges he doused his then-girlfriend’s 7-year-old son with flammable liquid.

The man’s own 15-year-old son then set the younger boy’s shirt on fire, Saxonburg police said.

Edward B. Myers, 35, allegedly used his cell phone to film the attack on May 25 at his Carol Drive home as he watched the boy burn.

Myers, the 15-year-old and his 11-year-old son, that same day of suspected torture, repeatedly shot the victim with airsoft guns and pellet-type guns, according to court documents.

The boy needed hospital treatment for third-degree burns on his face and chest, and welts on his forehead.

“I’ve seen a lot of horrible crimes against children during my career, but this one ranks among the worst of them,” said Saxonburg Police Chief Joe Beachem.

District Judge Lewis Stoughton on Wednesday arraigned Myers on felony assault and other charges. He is in the Butler County Prison on $250,000 bail.

The 15-year-old faces similar charges in county juvenile court, Beachem said.

Investigators are not sure what motivated the alleged sadistic attack, however, one of Myers’ sons reportedly claimed it was a “prank.”

But Beachem dismissed any claim that what happened was a prank.

“I’ve heard there was some animosity between Myers (and his sons) and the victim,” Beachem said, “but I don’t know what could motivate someone to do this.”