An apparent explosion injured a man in a Utah home where police had previously found a weapons stash and explosives.

Firefighters arrived at the South Jordan home on Saturday to find a middle-aged man with severe lower leg injuries, deputy fire chief Ryan Lessner said. Authorities have not identified the man, but the homeowner's sister claims her cousin was caught in a "booby trap" her brother likely left at the residence. 

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The home was investigated in July when homeowner Ryan McManigal was arrested on suspicion of firing a weapon at police officers and manufacturing explosives. Authorities reportedly found more than 4,700 rounds of ammunition in his home.

McGanigal’s sister, Bridget McGanigal Black, said her cousin Jacob had been working on repairs at the home when a homemade bomb went off.

“He threatened me that he was going to set up booby traps,” Black told FOX 13. “He told me that he was going to set up booby traps in my mom's house in Vegas so it doesn’t come as a surprise to me that he would do this in his own home.”

Lessner said it looked like there was an explosion of some kind inside the home. Authorities evacuated three nearby homes as a precaution, even though they saw no active fire.

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Explosives experts started an investigation at the scene, but Lessner said that he is “confident that there is no threat to the public.” The West Jordan Police and Fire departments are expected to release further details Sunday.

Ryan McManigal is currently in Salt Lake County Jail, KUTV reported.

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Investigators said they are still working to look into who the man was, what caused his injuries and working to make sure there are no further incidents.

The Associated Press contributed to this report.