Matthew Scott Alder, a safety volunteer, was charged with manslaughter Wednesday for fatally shooting bystander Arthur “Afa” Ah Loo during a June No Kings protest in Salt Lake City.

Alder fired three shots after seeing Arturo Gamboa, 24, carrying a rifle, believing Gamboa was about to commit a mass shooting; Gamboa was wounded but not charged, as his weapon was unloaded and pointing down.

Salt Lake County District Attorney Sim Gill emphasized that while individuals may have the right to use lethal force, it cannot be applied recklessly.

Gamboa had previously attended multiple protests armed with an AR-15-style rifle for self-protection and the protection of other demonstrators, The Guardian has reported.

Ah Loo’s widow praised the manslaughter charge as a step toward establishing safer conditions at public gatherings.