A house party that ended in a deadly beating was supposed to be small — just about 10 friends. Word quickly spread by e-mail and text and it swelled into an unruly 80.

When the parents of the high school girl hosting the party asked everyone to leave Saturday night, the crowd spilled into the street.

That's when a fight broke out between two females and two males, and one of the females hit a guy, said Maj. Tommy Wheeler of the Douglas County Sheriff's Department. In a case of twisted chivalry, the man decided he would not retaliate — but vowed to beat up the next man who passed by, investigators said.

That's when 18-year-old Bobby Tillman happened to come upon the crowd. Authorities said four teenagers swiftly stomped, kicked and punched him to death while dozens of bystanders watched. All four were charged with murder Monday.

"He had nothing to do with anything," Maj. Tommy Wheeler of the Douglas County Sheriff's Department said of Tillman. "They just decided he's the one. And they killed him."

Tillman had apparently come for the party but attended a different high school than most of the other young people and unwittingly became a target.

"It just got out of hand," said Cherola Butler, who lives across from the rented white house that hosted the party. "I couldn't sleep that night. It's just so hard to believe that something like this can happen so close to your house. I just hate that it happened. It could have been my daughter out there."

Dozens of witnesses were taken to the sheriff's office for questioning, and the four people were arrested.

Tillman's mother, Monique Rivarde, couldn't contain herself Monday during an initial hearing for the suspects, bursting into tears as soon as she set foot in the courtroom and wailing as prosecutors charged each man with fatally beating her son.

"He was an angel here on Earth, and I was blessed to be his mother," Rivarde said. "My son did not die in vain. My son is a silent hero. He touched so many lives I didn't know about. Bobby was a ray of sunshine through every dark cloud that anyone had."

The four suspects were identified as Quantez Devonta Mallory, 18; Horace Damon Coleman, 19; Emanuel Benjamin Boykins, 18; and Tracen Lamar Franklin, 19. None of them had an attorney in the courtroom, but some of their relatives were frustrated they had not been able to contact the men since their arrests.

"They haven't even allowed me to call him," said Erica Hillery, Mallory's mother. "I feel real bad for the victim's parents, but I need to know what's going on. If he's 18 or 35, he's still my son."

The parents of the girl who threw the party did not answer their door Monday in the middle-class suburb west of Atlanta. Douglas County Sheriff Phil Miller did not expect them to face charges. He said no drugs or alcohol were found in the house.

Kizzy Powell, who lives next door to the small white house where the party took place, said she rushed home after learning from her brother that police had strung crime scene tape near her house. She got home in time to see medics trying to save Tillman.

"It was terrible, and so many people watched it like it was a sport. I keep seeing it over and over," she said. "The saddest part to me is that no one helped. I wish I could have gotten home earlier and that my lights would have scared them."

Douglas County District Attorney David McDade said he will ask a grand jury to indict the men within two weeks. He did not say whether he would pursue the death penalty.

"I don't think you'll ever know why it happened. It's senseless," he said. "This is an absolutely unprovoked, senseless killing by young people killing another young man for no reason, no motive."