OROVILLE (CBS/AP) — Authorities are investigating a suspected bomb-making operation after a man was injured and a woman was arrested following an explosion at a Butte County home.

Nicholas West suffered injuries to his hands and legs in the blast March 19 in a rural neighborhood northeast of Oroville, the Butte County Sheriff’s Office said.

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Deputies evacuated the area as they searched the property and removed pieces of a detonated explosive device, a sheriff’s statement said.

Investigators believe West was trying to make some kind of bomb when the blast occurred, the statement said.

Deputies also found 20 firearms, ammunition and large quantities of narcotics. Four of the 20 guns were illegal assault weapons, officials said.

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Elizabeth Ellis

Elizabeth Ellis was arrested (Butte County Sheriff’s Office)

West, 26, was hospitalized in unknown condition.

Elizabeth Ellis, 55, was arrested on suspicion of possession of illegal assault weapons, possession of a controlled substance for sale, possession of an explosive device, and possession of materials necessary to make an explosive device. It wasn’t known Sunday if she has an attorney.

The investigation is ongoing and detectives expect to make more arrests, officials said.

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