"That it could have happened to anyone in the community is scary," she said.
Courtney Sullivan, also a senior at Standley Lake, said her father spoke to her and her younger brother about Jessica's disappearance.
"He's definitely talked to us about being more careful about our surroundings. You could see why," said Sullivan, a cross-country runner who often runs on neighborhood streets. "I'm running in places where there's lights, busy roads, where I can get to someplace if I need to," she said.
Fliers about the fifth-grader were posted on nearly every house in Jessica's neighborhood of modest, two-story homes with single-car garages. Purple ribbons, Jessica's favorite color and a symbol of hope for her return, were tied around trees.
It was a lively area where children played outdoors, said another neighbor, Luis Pena, but since Jessica disappeared, parents are keeping their children inside and people look at each other with suspicion.
"Nobody trusts anybody anymore," he said.
The only real clue police have revealed in Jessica's disappearance is the discovery over the weekend of a backpack and water bottle that she had with her when she disappeared. Police won't discuss what was found in the bag or test results on it.
The items were found in the town of Superior, some six miles from Jessica's home.
Additional police were sent to Jessica's school, said Lynn Setzer, spokeswoman for Jeffco Public Schools. The district has its own security officers at other middle schools and high schools.
Steve Saunders, a spokesman for nearby Adams County schools, said the district is trying to strike a balance between reassuring students and their parents that they are safe, while encouraging them to be vigilant.
Saunders said the district has security officers at all middle schools and high schools, but not elementary schools. He said the district will seek more help if authorities believe it is warranted.
Associated Press reporter Thomas Peipert contributed to this story.