Parents have been warned to keep an eye on their children and take extra safety precautions after a 17-year-old Southern California girl was apparently abducted about a block from her school and killed.

An autopsy confirmed the identity of Norma Lopez Wednesday, six days after she disappeared and a day after her decomposed body, shirtless and clad in jeans, was found face-down in a grove of trees in the agricultural area on the eastern edge of Moreno Valley.

Investigators would not release the cause of death.

Police and the FBI have not identified a suspect and asked the public for help in the investigation. Police would like to speak with the driver of a green SUV seen speeding from the area the day Lopez vanished.

About 2,000 people gathered around an athletic field at Lopez's school Wednesday evening for a vigil where friend Moises Michel, 16, remembered how Lopez loved dance, especially merengue and salsa.

"Whenever we were bored we'd just dance with each other, we'd get up and dance," he said. "I'm used to seeing her every day smiling. I'm just in shock because I can't believe it."

Lopez disappeared July 15 after leaving a summer school class at Valley View High School, where she would have been a senior this year. Authorities said she was heading to meet a friend.

When she didn't show up, her younger sister and a friend went to look for her, found some of her personal items in a field 1½ blocks from the school, and called authorities, said Riverside County sheriff's Sgt. Joseph Borja.

The field, a well-known neighborhood shortcut, is off a street that dead-ends at the base of boulder-studded hills cut with trails. Homes line one side, but in the blazing Wednesday heat, the expanse of dirt and dry stubble was deserted.

Searchers had fruitlessly covered the area for several days.

The mix of suburban-style residential sprawl and large rural areas is common in fast-growing Moreno Valley, a city of 186,000 about 60 miles east of Los Angeles between March Air Reserve Base and a swath of unforgiving, rugged terrain known as The Badlands.

The teen's disappearance drew wide attention across Southern California, where the high-profile abduction-murders of two other teenage girls in San Diego County — one jogging alone this year and the other walking to school in 2009 — led to a sex offender who ultimately admitted to the killings and is now imprisoned.

"I believe this has been made personal because we all have children," Borja said. "It's probably our worst nightmare that our kids can just be taken from a street and killed."

He would not provide details on the items found at the site where Lopez was abducted, explaining that releasing further details could hamper the investigation.

"We haven't caught the suspect who killed Norma so obviously there is at least a murderer out there, and so I would be vigilant, I would be aware," Borja said. "If I was a parent, I would keep track of my children. I would do everything I could to ensure their safety."