Two British teenagers went on trial Wednesday for allegedly plotting a school massacre inspired by the Columbine killings in the United States.

Prosecutors say Matthew Swift, 18, and Ross McKnight, 16, planned to bomb a shopping center before killing teachers and students at their school on the 10th anniversary of the massacre.

The teenagers were inspired by the April 1999 killings at Columbine High School in Colorado, where gunmen Eric Harris and Dylan Klebold killed 12 students and a teacher before committing suicide, prosecutor Peter Wright said.

Wright told a jury at Manchester Crown Court in northwest England that the defendants "planned to copy and emulate the actions of Eric Harris and Dylan Klebold," and wrote up detailed plans for the massacre, which they called "Project Rainbow."

McKnight wrote in his diary of carrying out the "greatest massacre ever."

"We will walk into school and at the end of it no one will walk out alive," he wrote.

The jury also was told that a safe in Swift's bedroom contained plans of the school and instructions on using acetone peroxide as a detonator. The safe also contained a notebook that contained plans, jottings and an image of Harris and Klebold taken from closed circuit camera footage during the Columbine attack.

Underneath was written: "They say a picture paints a thousand words. This is my favorite picture in the whole world."

The defendants deny the charges.