ALTOONA — The roommate of a Penn State student from Russia charged with building a suspected bomb in his bedroom says the 18-year-old recently set off three “mini-bombs” just outside their apartment.

Andrew Leff said he had advised Vladislav Miftakhov to get rid of the bomb-making materials. He called Miftakhov a “dumb” and “crazy” kid who was bored and impulsive, but not dangerous.

“He was off the wall,” Leff said.

Miftakhov, a student at Penn State’s satellite campus in Altoona, was in jail Sunday after being arrested Friday and charged with possessing a weapon of mass destruction, risking a catastrophe and several other drug and weapons counts, according to court records. The records did not list a lawyer for Miftakhov, who was being held on $500,000 bail.

In the affidavit, police said they were investigating a reported marijuana growing operation at Miftakhov’s apartment reported by the landlord when they found a suitcase holding two containers with exposed fuses and other explosives-related materials. The devices were later dismantled by state troopers.

An Altoona Police officer in the apartment asked Miftakhov what he was going to do with the devices and Miftakhov responded that he was going to “blow things up,” according to the affidavit. Later, under questioning at the police station, Miftakhov said he had experimented with the devices in California, but never in Pennsylvania.