Sioux Falls Police arrested an apparent antifa radical on Tuesday after finding a “concerning” number of illegal firearms and bomb-making materials in his apartment while serving a search warrant in connection with three area burglaries. Police also found antifa-related items during their search, including an antifa jacket and an anti-police manifesto. Authorities reportedly evacuated the surrounding area and called the Sioux Falls Police bomb squad.

A more in-depth story about the ANTIFA bomber arrested in Sioux Falls….#MAGA https://t.co/jSlG6EcqFt — Kevin O'Keeffe (@Xervosh) July 19, 2018

“The amount of explosives found was significant and concerning,” Minnehaha County Sheriff Mike Milstead said.

Mark Einerwold, 43, was arrested “on multiple burglary charges and for the sale or transportation of a destructive device,” KDLT News reported.

Authorities say they found multiple explosive devices as well as aluminum nitrate and aluminum powder, which authorities say have no use other than for an explosive device. Authorities also seized multiple firearms and a homemade firearm silencer from the residence.

Einerwold said he was $350,000 in debt and had no assets in his application for a court-appointed attorney.

In court, prosecutors said that police found a pistol, sawed-off shotgun and a silencer in a backpack in Einerwold’s home. In addition, police reportedly found a “manifesto” that issued threats toward law enforcement and the government.

Captain Jason Gearman with the Minnehaha County Sheriff’s Department said they also found an “antifa” jacket and “indications of extreme hatred for the police, fire and the government.” Antifa is a militant movement of extreme left-wing anarchists who often use violent means to protest right-wing and “fascist” organizations and ideas.

Police also found an improvised explosive device in Einerwold’s vehicle, according to KELO.

“Pretty safe to say that we stopped something from happening,” Gearman said. “Again, we don’t know what that is.”

Authorities said the investigation is ongoing and more charges could be coming.