Guns. metal-piercing bullets and drugs were found on the plane that rapper Juice Wrld was travelling on before his sudden death.
Authorities said federal agents and police had been tipped off and were waiting for the private jet to land in Chicago on Sunday.
The award-winning music star, 21, and about a dozen other people were on the plane when it landed from LA at around 2am.
Juice Wrld, real name Jarad Anthony Higgins, fell ill shortly after touching down and was taken to hospital, where he later died.
The hangar where the plane landed was being searched when Higgins went into convulsions, and a dog found luggage carts with bags of suspected marijuana.
Chicago police spokesman Anthony Guglielmi said three guns, metal-piercing bullets and a high-capacity ammunition magazine had also been found – plus several bottles of prescription cough medicine.
Two security guards who were on the plane have been arrested on gun charges but none of those on board have admitted to carrying the drugs, with analysis under way to determine who owned which bags.
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Toxicology tests are also being carried out to find out how Higgins died.
Medical officials are waiting for the results before drawing any conclusions from Monday’s post-mortem examination, but foul play is not suspected.
Higgins did wake up after his convulsions when he was given Narcan – a medication to block the effects of opioids.
He remained incoherent after waking up and was rushed to Advocate Christ Medical Centre in Oak Lawn, where he was pronounced dead.
His girlfriend told officials he had been taking Percocet, an opioid painkiller.
Fans and fellow rappers have paid tribute, with British star DJ Semtex describing him as “mad cool, insanely talented, and just getting started”.
Higgins, who was from the Chicago suburb of Homewood, was considered a rising star and was named top new artist at the Billboard Music Awards in May.