Sean Ernest Ruis, 43, walked into Quality Dairy in Windsor Township — just outside Lansing and 100 miles west of Detroit — at about 6:45 a.m. without wearing a mask.
A 77-year-old customer asked Ruis to cover his face and the store refused service before asking him to leave, Michigan State Police said in a statement. He then stabbed that customer who asked him to put on a mask, authorities said.
Police issued an alert with a description of Ruis' car and his license plate number, authorities said. A short time later, an Eaton County Sheriff's deputy pulled over Ruis on a residential street in neighboring Delta Township at 7:13 a.m., leading to the brief, fatal encounter, official said.
"The suspect immediately exits his vehicle and walks towards the deputy with a knife in hand to attack the deputy," according to a statement from state police. "The deputy attempted to increase distance by backing up and subsequently shot and injured the suspect. The suspect was transported to a local hospital and died during surgery."
Both the Eaton County Sheriff's Department and state police released graphic video of the deadly confrontation, which appeared to show a man approaching the deputy. The deputy could be heard screaming "Drop the knife!" and "Drop the weapon!" several times in the footage.
The sheriff's 10-second video appeared to be from the deputy's body camera and she could be seen backing up while ordering, "Drop the weapon, drop the weapon!"
The deputy appeared to fire several times at the man, who kept approaching despite being shot.
"She backed away from him while repeatedly ordering him to drop the weapon, but he continued to advance and attack and she acted in defense of her life," according to a sheriff's statement.
"Our thoughts and prayers are for the full recovery of the victim who was stabbed at the Quality Dairy and for his family, and are with our deputy who was subsequently violently attacked. They are also with the family of Mr. Ruis who was killed in this senseless, tragic incident."
The sheriff also released a picture that seemed to show the man with a stabbing weapon in each hand.
And just before the deputy opened fire, the man was well within reach, Eaton County Sheriff Tom Reich said.
"You can see in that one photograph I gave you, how close the assailant came to her," Reich told reporters. "You can't see the deputy's weapon but it was covered by the assailant's hand."
The deputy has been placed on administrative leave as standard practice in an officer-involved shooting, according to the department.
Ruis lived in nearby Grand Ledge and the Eaton County Sheriff's Department did not immediately identify its deputy — though state police called her a 22 1/2-year veteran of the force.
She was not injured in the confrontation, officials said.
Ruis had been employed as a transportation technician for the state Department of Transportation since 2008, the agency said.
"He was a transportation technician in mix design, which is responsible for pavement design procedures, investigation, training and testing," according to a statement by DOT spokesman Aaron Jenkins.
The man stabbed at the store was taken to a local hospital and is expected to survive, state police said.
Tuesday was the second day of a state order, in light of the ongoing pandemic, making face coverings mandatory in any indoor public setting or any outdoor location in Michigan where there cannot be proper social distancing.