An Indiana firefighter was shot dead without explanation Monday after stopping to help a stranded motorist.

Kentucky resident Justin Moore, 31, was traveling in Indiana when he ran out of gas around 9:30 p.m. Zachary Holly, a police officer with the Palmyra Police Department, arrived at the scene to offer assistance. Not long after the officer's arrival, Jacob McClanahan, 24, pulled over to offer his help, according to Indiana State Police. McClanahan was a volunteer firefighter and Harrison County Highway Department employee.

Holly asked Moore if there were any weapons in his car, and Moore said no, police say. Moore was asked to place a small knife he was carrying inside his vehicle. 

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Moore then retrieved a shotgun from the vehicle and fired at Holly. The officer returned fire, fatally shooting Moore, but not before McClanahan was fatally struck by a shotgun round from Moore, police say.

The scene where Indiana volunteer firefighter Jacob McClanahan stopped to help a stranded motorist

Indiana volunteer firefighter Jacob McClanahan was killed Wednesday, May 18, 2022, by a stranded Kentucky motorist he stopped to help, police say. (Indiana State Police)

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Emergency response teams attempted to render aid to both McClanahan and Moore, but were unable to save either man. Holly suffered only minor injuries.

"Nothing makes sense that anyone could be murdered while stopping & rendering aid. Jacob is a true hero that will forever be remembered living the selfless life he did," the Harrison Township Fire Department wrote on social media Tuesday. 

Indiana volunteer firefighter Jacob McClanahan

Indiana volunteer firefighter Jacob McClanahan was killed Wednesday, May 18, 2022, by a stranded Kentucky motorist he stopped to help, police say. (Harrison Township Fire Department)

"A true firefighter that was always there when you needed help. Godspeed Jacob T. McClanahan. Your brothers at Harrison Township will miss you. Gone but never forgotten," the department added.

Officials still do not know why Moore was traveling in Indiana or why he decided to open fire on those assisting him.

Indiana volunteer firefighter Jacob McClanahan with two other firefighters

Indiana volunteer firefighter Jacob McClanahan, right, was killed Wednesday, May 18, 2022, by a stranded Kentucky motorist he stopped to help, police say. (Harrison Township Fire Department)

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A GoFundMe to cover McClanahan's funeral expenses has raised nearly double the $10,000 goal, and Indiana Gov. Eric Holcomb directed flags in Indiana be flown at half staff in Harrison County to honor McClanahan.