Brian Cox / Special to the Tribune

Winnetka police are crediting alert citizens with helping in the arrest of two 15-year-old boys who were charged with aggravated battery and possession of stolen property in excess of $300 after a woman was assaulted while walking on the Green Bay Trail last week, authorities said Wednesday.

 A 20-year-old female Kenilworth resident was walking in the 200 block of the Green Bay Trail at around 4:30 p.m. July 21 when two 15-year-old boys on bikes passed her several times, police said. On the last pass one of the boys struck the woman on the upper body with his hand and the two juveniles rode away on the trail south bound, said police.

 The victim yelled out and called 911 with a description of the juveniles, police said. A Winnetka police dispatcher immediately broadcast a description of the juveniles and they were picked up a short time later by a Kenilworth police officer and subsequently identified by the victim as her attackers.

  “Had it not been for her ability to provide us with a description that Kenilworth officers probably would not have been able to make that connection,” said Winnetka deputy chief Patrick Kreis.

 Police also quickly determined that one of the juveniles was riding a $400 bike that had been stolen in Winnetka two day earlier.

 “The victim from the bike theft not only reported the bike theft immediately but they had kept the serial number of the bike and were able to provide it to police when it was stolen,” said Kreis. “The Kenilworth officer ran the serial number and it came up as stolen. We were able to return that bike to its owner just two days after it had been taken.”

He said the woman was not seriously injured. He added that investigators are not sure what motivated the assault.

Both juveniles are from the New Trier Township area and one has been petitioned to juvenile court on an aggravated battery charge while the other is charged with possession of a stolen property in excess of $300.

 “It was good police work but it only occurred because we had two heads-up active citizens,” Kreis said.