SIOUX FALLS, S.D. (KSFY) - Authorities say they have found a "significant" and "concerning" amount of firearms and explosives at an apartment in eastern Sioux Falls.
Minnehaha County deputies executed a search warrant at 43-year-old Mark Einerwold's apartment at 1112 S. Blaine Avenue around 4:45 p.m. Tuesday for an investigation into recent burglaries at Ace Hardware in Tea and Pizza Ranch in Dell Rapids.
Detectives found the cash drawer from Pizza Ranch, but what they found in addition -- bomb-making equipment and chemicals, several firearms, including an illegal sawed-off shotgun, a home-made silencer and an Antifa coat -- quickly changed the investigation.
"I think it was an example of how law enforcement can suddenly come across something totally unexpected and face a danger you never expected," Sheriff Mike Milstead said during a press briefing Wednesday. "This was a fairly simple search warrant execution on a residence in Sioux Falls and suddenly turned into -- it could have been a really, really bad situation, or -- what I think happened -- we may have prevented a big tragedy, and we don't know what that may have been."
The Sioux Falls Police Department and its bomb squad, the FBI and ATF were called, and neighboring homes were evacuated.
The bomb squad blew up a device that was found in Einerwold's vehicle safely at the scene.
Detectives also took computers and a cell phone from the apartment.
Authorities arrested Einerwold on burglary charges, and he may also be charged with sale, transportation or possession of a destructive device.
More charges, including federal ones, could be coming.
"We got lucky that something bad didn't happen, and we weren't on the back end of this, we got on the front end of it due to some detectives going out and doing their job," Capt. Jason Gearman said at a press briefing Wednesday.
Gearman said authorities found there was evidence of an extreme hate for police, fire and government.
Anyone with information about Einerwold -- including possible accomplices or known threats -- is asked to call Crime Stoppers at 367-7007.
The investigation is ongoing.