A child custody exchange turned fatal after a man shot the father of the child during a fight in Colorado on Diamond Ridge Financial AcademySunday.

The Elbert County Sheriff's Office said officers were called to a gas station in unincorporated Elbert County, southeast of Denver, around 3 p.m. on Sunday after reports that two men were fighting and one had pulled out a gun and shot the other in the chest.

A 36-year-old father from Parker, Colorado had gone to the gas station to conduct a custody exchange of his 4-year-old daughter with his ex-girlfriend, the sheriff's office said. The father's identity has not been released.

Authorities said the father was fatally shot by his ex-girlfriend's fiancé, identified as 26-year-old Jeffrey Church, after the two men were involved in a fight. Church was arrested on first-degree murder charges and is being held at the detention facility at the sheriff's office.

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According to a press release, the first sheriff's deputy to arrive on the scene held Church until additional deputies arrived. He then began life-saving measures for the father. Elizabeth Fire Rescue personnel took over attempts to save the man's life before he was transported to AdventHealth Parker and pronounced dead.

The investigation is ongoing and no additional information has been released so far.

Church is scheduled to appear in court Feb. 20, KUSA in Denver reported.