Florida police are investigating the theory that the rapper was killed by two armed robbers on Monday night.
Kanye West was one of the first to pay tribute to the fallen star last night with this poignant note: "Rest in peace ??? I never told you how much you inspired me when you were here. Thank you for existing."
According to TMZ, XXX was shot and left for dead as he was leaving a motorcycle dealership where he'd been checking out new rides. Witnesses said a Louis Vuitton bag was taken from XXX's vehicle.
Police described the two suspects as "two males wearing hoodies and driving a black Dodge Journey".
"Witnesses say they heard multiple shots fired," one source told TMZ.
The hip hop star was pronounced dead after being rushed to hospital in a "comatose" condition, according to media reports.
The Broward County Sheriff's Office confirmed the rapper was dead by tweeting the news late last night. "The adult male victim has been confirmed as 20 year old Jahseh Onfroy aka rapper #XXXTentacion," they wrote.
Macabre photographs of XXX apparently dying and slumped over in his car outside the dealership are now circulating online.
XXXTentacion, who had a staggering 5million subscribers to his YouTube channel, started writing music after being released from a youth correction centre and eventually released his first song on SoundCloud in June 2013, titled "News/Flock".
XXXTentacion released his debut album, '17' in 2017 and his second album, '?'' was released earlier this year and debuted at number one on the Billboard 200, with its singles 'Sad'" and 'Changes' peaking at numbers seven and 37 on the Billboard Hot 100 respectively.
XXX, who had served six months in prison in 2015 on armed home invasion charges, was awaiting trial for domestic violence on his pregnant girlfriend.

rest in peace ??? I never told you how much you inspired me when you were here thank you for existing pic.twitter.com/QU7DR3Ghbw

— KANYE WEST (@kanyewest) June 18, 2018