It was supposed to be a harmless water gun fight. Daquan Rueben Gillett, his twin brother and their friends were celebrating their upcoming graduation from Riverdale High School.

But 20-year-old Sean Allen had a real gun at Kenwood Park in Fayette County, according to investigators. And that’s when the fun turned deadly.

On Sunday, Allen was convicted of murder and aggravated assault and sentenced to life in prison, the Griffin Judicial Circuit District Attorney’s Office said. The deadly shooting happened May 7.

“As they were playing with their water guns, a group of males led by Sean Allen walked down from the basketball court and engaged in a verbal confrontation with the twin brothers,” the DA’s Office said in a news release. “Sean Allen and another one of his friends were both illegally carrying loaded firearms at the time.”

That led to a physical fight and Allen dropped his gun, according to investigators. When the fight ended, Allen picked up his gun. But then, he started another fight with Gillett, 18, prosecutors said.

Daquan Gillett, 18, died after being shot May 7 at a Fayette County park, according to police.

Credit: Family photo

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Credit: Family photo

When Allen again dropped his gun, Gillett picked it up and walked away from the fight, the DA’s Office said.

“Subsequently, Sean Allen grabbed the second firearm and ran towards the victim firing multiple shots in his direction,” the DA’s Office said.

Gillett was shot in the back of his leg and in the back of his head. Allen and his friends left the park, according to investigators. But he was arrested later the same day and charged with murder after Gillett died from his injuries at Piedmont Fayette Hospital, the Fayette sheriff’s office previously said.

The fight and shooting were captured on park cameras, according to prosecutors.

“This case is a reflection of a growing trend in this circuit and across the state where altercations turn deadly because of the unlawful use of a firearm,” District Attorney Marie Broder said. “The results for the young people involved in this case were tragic.”

In addition to his twin brother, Gillett is survived by his parents and two sisters, according to a GoFundMe page created by one of his sisters.

“Anyone who has had the opportunity to meet my brothers knows that they are always soooo full of joy,” Deashia Gillett posted on the fundraising page.