Spanish police seized more than 300 pounds, or 140 kilograms, of explosive materials when they arrested the suspect.

Story highlights

Police began investigating man 5 months ago after Internet messages about Columbine

Police tracked his efforts to acquire explosive materials via the Internet

Suspect arrested Wednesday as he received the materials at his home, police say

In his personal diary, "he showed a hatred for society," police say

Madrid CNN  — 

Inspired by the deadly Columbine school shooting, a Spanish man purchased more than 300 pounds of explosive materials as part of an alleged plan to massacre university students, authorities said Thursday.

Instead, Spanish police, who had been tracking him for five months, descended on his home Wednesday morning and arrested the 21-year-old just as he received the potentially deadly materials he had ordered off the Internet, according to authorities. They seized 140 kilograms of the materials.

Police arrested the man in Palma de Mallorca, not too far from the University of the Balearic Islands, where they say he planned his attack. Mallorca is one of Spain’s Balearic Islands, off its southeastern coast in the Mediterranean Sea.

Police have not released the suspect’s name, but they say he was a student at another educational center where he studied business administration. Although they believe he planned his attack at the University of the Balearic Islands, he had sent a threatening letter to his school, a police statement said.

Police say the suspect planned his attack at the University of the Balearic Islands, pictured here.

Documents taken from his home, including his personal diary, indicated he wanted to imitate the 1999 U.S. massacre that left 15 dead at a high school in Columbine, Colorado, according to police.

“He showed a hatred for society, especially for university students, and his decision to strategically place pipe bombs filled with shrapnel on the university campus,” according to the police statement, referring to the documents seized from the suspect’s home.

“He also admitted the hypothesis of suicide while carrying out the massacre,” the statement added.

Police began investigating the suspect five months ago after detecting Internet messages alluding to the Columbine massacre.

“The suspect showed a sympathy” for the two men who carried out the Columbine attack, the statement said.

His blog included sections showing that he knew how to make bombs, displaying the same musical tastes as the Columbine killers, describing his interest in weapons and mentioning “social isolation that led to situations of feeling left on the sidelines at school,” the statement said.

Read more: Nothing the same after Columbine, say students, teachers

The suspect sought to acquire weapons illegally and later applied for a license to legally possess weapons, a document that is hard to get in Spain. The application was rejected.

Police tracked his subsequent efforts to acquire the explosive materials through the Internet before arresting him Wednesday.

The suspect “is not part of any political party or association,” according to Teresa Palmer, a central government representative in the Balearic Islands.

She called it “a completely isolated event” and encouraged citizens to remain calm.

Complete coverage: Theater shooting in Aurora

Read more: Norway killer Anders Breivik ruled sane, given 21-year prison term