Chicago, Ill - Two second-grade girls who disappeared while riding bikes together were found dead Monday, both stabbed multiple times and left to die off a bicycle path in a park, authorities said.

A resident walking through a wooded nature area in the park discovered the bodies of best friends Laura Hobbs, 8, and Krystal Tobias, 9, at dawn.

"This is a heinous crime. It was a crime not only against those kids but against all of us," Police Chief Doug Malcolm said.

The parents of one of the girls had reported her missing about 8:50 p.m. Sunday, about two hours after she was expected home, Malcolm said. The parents of the other girl called shortly afterward, and authorities with rescue dogs began searching.

Malcolm said no weapons were found and there was no evidence of sexual assault. A girl's bicycle was found nearby. He said police had not identified any suspects and that there were "no solid leads that we're focusing on."

The killings stunned this town about 45 miles north of Chicago, prompting police and school officials to escort children directly onto buses at the end of the school day. Dozens of anxious parents waited until their children emerged from the front doors of the school, then put their arms around their kids or clutched their hands as they walked to their cars.

Fifteen-year-old Albert Tobias said he didn't know why someone would want to attack his sister. "But I would like to know what happened," he said in a brief telephone interview.

Constance Collins, superintendent of the Zion Elementary School District 6, said the girls were in the same second-grade class at Beulah Park Elementary School.

"They were best friends," said Laura Unrein, who lives near the park. "When one left, the other left. They were always together."

"They were very sweet girls," said Julie Dobnikar, who teaches second grade at the school. Dobnikar added that the girls' teacher is "very distraught right now."

School was in session Monday, and social workers and a crisis intervention team were called in to help the students.

Jeanette Ortiz said she is worried because her 11-year-old son plays and rides his bike in the same park. She came to the school to pick him up.

"I'm going to have to tell him that he needs to be careful no matter where he goes," she said.

Unrein said the area where the girls' bodies were found is well-known in the community as a place to avoid.

"There have been incidents of kids beating up people and taking their wallets and park rangers have had to shoo people out of there for hunting illegally," she said. "My husband and I don't go down there any more because you hear the stories."

The park where the girls were found has a paved bike path, a ravine and trails made by mountain bikes. Police tape cordoned off the area.

Zion, along Lake Michigan, was founded in 1901 by a religious faith healer as a utopian community. It has about 22,000 residents but retains a quiet, at times rural feel despite being on the edge of both the Chicago and Milwaukee metropolitan areas.