A Michigan sheriff's deputy on Tuesday fatally shot a man suspected of stabbing another man who had challenged him about not wearing a mask at a store, police in the United States said.
The shooting occurred in Eaton County, south-west of Lansing, about 30 minutes after the stabbing at a Quality Dairy store, state police Lt Brian Oleksyk said.
A sheriff's deputy spotted the man's vehicle in a residential neighbourhood and shot him when he got out of his car and tried to attack her, Lt Oleksyk said.
"Drop the weapon! Drop the weapon!" the officer, a 22-year veteran, demanded, according to neighbourhood security video released by police.
The man, Sean Ruis, was holding a screwdriver and knives, Eaton County Sheriff Tom Reich said.
"It's very unfortunate she had to use her weapon, but she had to save her life," Sheriff Reich said.
"She had to use deadly force. She did it properly."
Mr Ruis, 43, of Grand Ledge, who worked at the Michigan Department of Transportation, died at a hospital. He was suspected of stabbing a 77-year-old man inside the store when he was confronted about not wearing a mask, Lt Oleksyk said.
The stabbing victim was in a stable condition at a hospital.
Michigan State Police have released complete footage of the fatal shooting on Twitter (below). The video was tweeted with a warning about the sensitive footage.
Governor Gretchen Whitmer has ordered people to wear masks in stores to reduce the risk of spreading coronavirus.
"The goal here is to be safe. We all have to do our part so this doesn't spread," Sheriff Reich said.
The decision about whether to wear a mask in public for some has become a political statement, and there have been other violent encounters. In May, a security guard at a Family Dollar store in Flint was fatally shot after denying entry to a customer without a mask.
Senate Majority Leader Mike Shirkey said masks are important. But he also urged the general public not to confront people over a lack of a mask.
"There is no reason to risk your health or your life over the debate of wearing masks in public," Mr Shirkey said.
In May, Donald Trump ignited a new feud with the attorney general of Michigan, Dana Nessel, after she called him a "petulant child" for refusing to wear a face mask in public on a visit to the state.
Meanwhile, Michigan's Democrat governor Gretchen Whitmer is seen as a potential vice presidential running mate for Joe Biden, the presumptive Democrat nominee.
She has faced a strong backlash from anti-lockdown protesters, many of whom support Mr Trump.
Ms Whitmer's national profile was boosted when she became a target for Mr Trump, whom she has frequently criticised for his response to the coronavirus pandemic.