Story highlights The teens all attended the same high school

Police say the killing was planned

Two 16-year-olds are charged with murder.

Police became suspicious when they found a car backed up to the woods

Ask a simple question.

Police in Wylie, Texas, wanted to know what two teenagers were doing in the woods Saturday night.

"We are burying a body," one of them said.

They weren't kidding. When police looked in the woods northeast of Dallas they found the corpse of 17-year-old Ivan Mejia of Wylie. The two 16-year-olds were charged with murder.

Police first became interested when they checked out a suspicious, unoccupied vehicle backed up to the treeline, according to a department statement. Officers went into the woods and saw two suspects running from the area.

Police returned to the car and the 16-year-olds walked up and answered the question that set off bells, the statement said.

Mejia was killed behind Wylie East High School, where all three teenagers were students, and taken to the wooded area, police said. No motive has been released, but police say the killing was planned.

The school system said the incident was not connected to a school-sponsored activity.