A man suspected of planning an attack on the University of the Balearic Islands is being held by Spanish police in Palma de Mallorca.
The suspect, a student, aged 21, was detained after obtaining 140kg of explosive material bought over the internet.
The BBC reports he kept a diary where he wrote about hating society and that he was ready to die in his attack.
The suspect is believed to have been planning to plant pipe bombs on campus. He was identified only by his initials, JMMS.
Police began investigating five months ago after finding comments online about the Columbine High School massacre in the United States, when two former pupils murdered 12 students and a teacher.
A statement said the suspect expressed sympathy for the teenage killers, Eric Harris and Dylan Klebold.
He is said to have initially tried to purchase guns, but then opted for bombs and was arrested at 10.30am on Wednesday when he received the explosives.
Police issued a photo of the ingredients, including ammonium and potassium nitrate, both used in fertilisers; sulphuric and nitric acid; and sodium sulphide.
UIB, which is located in Palma, has 16,400 students.