UPDATES THROUGHOUT with comment from suspect's lawyer:

BELLEVILLE -- The second attacker of a 17-year-old student on a Belleville West bus flashed apparent gang signs after the beating, a prosecutor argued today in court.

The first attacker, a 14-year-old, appeared before St. Clair County Judge Walter Brandon late this morning for a detention hearing. Authorities argued for holding the attacker until trial.

"This is shocking in its violence and its brutality," said William Clay, an assistant state's attorney. Clay did not offer further explanation about the gang signs.

Brandon released the teenager to his father's custody, who is a pastor, on a 24-hour curfew. The teen must get a court order if he wants to leave his father's home for something other than attending school.

Both boys were charged with felony aggravated battery on Friday. The first attacker pleaded not guilty this morning in a Belleville courtroom, where Brandon found probable cause for the counts of aggravated battery.

Illinois law shields the disclosure of the names of juvenile offenders because they are minors.

Video of the attack was released last week by Belleville police. It showed a 17-year-old student being beaten on a school bus at various times by two other students while other passengers cheered . Police initially said the attack was racially motivated, but they later recanted. The victim is white and the suspects are black.

John Hipskind, the teenager's public defender, said stressed that the teen is "innocent until proven guilty" and that he has no prior juvenile delinquency cases. Hipskind said the teen made good grades before the attack and attended school regularly.

The victim was treated by a school nurse after the beating and later was released to his mother.

Clay said the victim "never provoked" the attack. He said he simply was looking for a place to sit on the bus.

Clay said the first attacker "clearly lost control that day."

"He was going to beat that victim until he was tired," Clay said.