'Below Deck' Alum João Franco & Brother Karlos Arrested in Turkey After Deadly Brawl: Report

"Below Deck" alum João Franco and his brother Karlos have been arrested in Turkey after a fight with shopkeepers turned deadly ... according to a bombshell report.

The incident went down in a clothing store in the city of Muğla Saturday night ... Page Six reported.

Local reports say that João and Karlos had used profanity in the store before the argument erupted.

Security footage obtained by Page Six allegedly shows Karlos throwing the first punch in a chaotic fight that saw chairs thrown.

While João mostly tried to break up the fight, he allegedly swung his fist at one point, before a store employee fell to the ground.

According to local reports ... the employee who fell to the ground was 17 years old and suffered a severe injury to the head before going into cardiac arrest.

After being transported to a nearby hospital ... he died from his wounds, Haberler.com reported.

João and Franco have since been arrested by Turkish authorities after being brought to Bodrum Courthouse ... and are now in jail.