LONDON — Two British teens were acquitted of a plot to carry out a massacre at their high school in a Columbine-inspired attack despite police evidence of the pair allegedly making explosives together.

Matthew Swift, 18, and his friend Ross McKnight, 16, were cleared of what prosecutors had alleged was a plan to slaughter students and teachers at the school in Manchester, in northwest England, on the 10th anniversary of the U.S. high school shootings.

The jury took less than an hour to deliberate at a Manchester court before reaching a verdict. It was a stunning blow to prosecutors and police, who had enlisted U.S. investigators who worked on the Columbine case to help them.

Police said they found footage of the pair making explosives together, as well as a cache of extremist literature, a bomb-making manual and sketches of the school layout at Swift's home.

Both teens shared a fascination with the Columbine killings and repeatedly alluded to plans for mass violence.

McKnight's diary referred to "the greatest massacre ever" while notes found in Swift's bedroom read: "Eric Harris, Dylan Klebold will rise again" — a reference to the teenage killers who slaughtered 12 students and a teacher at their Colorado school before committing suicide in April 1999.

But no weapons or explosives were ever found. Both teens argued that the police evidence was proof of nothing more than adolescent fantasy.