A man allegedly tried to stab a police officer before he was fatally shot outside the Riverton Walmart store on Saturday, authorities say.

That information comes from numerous eyewitnesses who have been interviewed by the Wyoming Division of Criminal Investigation, according to Fremont County Attorney Patrick LeBrun.

In a statement Monday, LeBrun said the Riverton police officer was trying to arrest the man for "observed violations of law," though LeBrun did not detail those violations.

Rather than give himself up, the man -- identified as a member of the Northern Arapaho Tribe, according to tribal officials -- drew a knife roughly six inches in length and stabbed the officer in the center of his chest.

"However, the officer's body armor stopped the knife from penetrating," LeBrun said.

Still armed with the knife, the man allegedly continued the assault, and the officer shot him. The man died at the scene.

The investigation is ongoing, LeBrun said.

DCI investigates all officer-involved shootings in Wyoming.