(CNN) An FBI bomb technician was wounded by a booby-trapped wheelchair on an Oregon property that was littered with trip wires, animal traps and a circular hot tub set to roll towards intruders like the boulder in "Raiders of the Lost Ark," according to court documents.

The property's former owner, who lost it in a civil judgment, has been charged with assault of a federal officer.

The special agent and three Oregon State Police bomb technicians went to the Williams, Oregon, house last month after Joseph Charter, the attorney appointed to sell the property as part of a civil lawsuit, found a sign warning that it was "protected by improvised devices."

Charter told CNN that he saw the sign when he went to check out the property August 29, but didn't see any obvious traps. When he came back the next day with a locksmith and a private investigator, they drove over nail-studded strips of wood that had been placed in the driveway, damaging the locksmith's tires.

FBI agent shot by booby-trapped wheelchair inside southern Oregon home https://t.co/nynsYFse0f pic.twitter.com/FqK7bsLc4K — The Oregonian (@Oregonian) October 2, 2018

When the FBI agent and police visited the property on September 7, they found it protected by a variety of devices set to ambush intruders.

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