Aurora police arrested a man after he allegedly shot and killed his older brother during an argument between the two on Tuesday evening, according to the Aurora Police Department.

Officers first responded to a 911 call about a shooting involving two brothers in the 1800 block of South Fairplay Street just after 6:30 p.m. Tuesday, the APD said in a Tuesday night news release.

Officers detained the younger brother, identified as Zackery Williams, 32, upon arriving at the scene without further incident, according to the news release.

Investigators believe that the two brothers armed themselves as the argument escalated — the elder brother with a knife, and the younger with a gun — before the shooting took place, according to the release. The older brother who died was 36, police said. His identity will be released by the Arapahoe County Coroner’s Office pending family notification and an autopsy.

The department said the incident is under investigation and that updates will be shared as they become available.