Shirley Pfeil was standing in the kitchen of her home in Riley Township about 12:43 p.m. Sunday when the fatal bullet flew through her window, police say

A suspected stray bullet struck and killed a 73-year-old Michigan woman on Sunday afternoon while she was having coffee in her kitchen with her husband after church, PEOPLE confirms.

Authorities believe the gunfire was from a neighbor’s target practice.

Shirley Pfeil was standing in the kitchen of her home in rural Riley Township in St. Clair County about 12:43 p.m. when the fatal bullet flew through her window, Michigan State Police Lt. Dave Kaiser tells PEOPLE.

Pfeil’s husband heard “a loud crack” as she collapsed, says Kaiser. She was rushed to the hospital but died from her wounds.

Kaiser says a subsequent investigation revealed that Pfeil’s 21-year-old neighbor was using his gun for target practice in his backyard and shooting toward a dirt berm, or embankment.

Police have not released the identity of the shooter as he has not been charged with a crime, Kaiser says.

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The man is “being very cooperative with the police,” he says, and is “devastated to learn that it was one of his bullets that killed this lady.”

“It’s so sad,” one local resident tells PEOPLE.

Authorities have seized the weapons the neighbor was using as part of their investigation, Kaiser says. Some of the bullets they collected as well as the weapons will be sent to a police crime lab to match the bullet up to the rifle.

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“Once our investigation is done and all the evidence is collected and the facts are gathered, we will submit it to our prosecuting attorney for review for potential criminal charges,” he says. (PEOPLE’s to prosecutors were not immediately returned on Monday.)

The 21-year-old could be charged with reckless discharge of a firearm causing death, according to Michigan state law, Kaiser explains.

Anyone shooting target practice should have a backstop in place to catch stray bullets, he says.