Five boys, aged 16 to 18, were arrested after a message on a website warned students at the school in Riverton to wear bullet-proof vests on 20 April.
Police said they found guns, bullets and knives at the home of one suspect.
In 1999, two pupils shot dead 12 fellow students and a teacher before killing themselves at Columbine in Colorado.
The alleged plot at Riverton High was foiled after a message was posted on My Space.com, a website popular with teenagers. The message said the attack would target a dozen students and a member of staff on 20 April, which is also Hitler’s birthday. A student e-mailed a friend in North Carolina with the rumours and she rang the police.
Authorities said the suspects planned to wear black trench coats just as Eric Harris and Dylan Klebold had done when carrying out the Columbine massacre…