Police found bottles of prescription codeine and a large amount of marijuana on the plane carrying rapper Jarad Anthony Higgins, also known as Juice WRLD, shortly before he died Sunday.

Police and FBI agents arrived to meet Higgins' plane at about 1:30 a.m. CT at Midway Airport on Sunday on the suspicion the rapper was in possession of contraband, the Chicago Police Department said Monday. Officers found 70 pounds of marijuana and six bottles of prescription codeine cough syrup in a search of the luggage on the twin-engine Gulfstream jet.

There were also two 9 mm pistols, a .40-caliber pistol, a high-capacity ammunition magazine and metal-piercing bullets found on the plane, according to police.

Though circumstances leading to the 21-year-old rapper's death are still unclear, police said Higgins began convulsing while police officers were speaking to him and others on the plane. He was given two doses of Narcan, a brand of naloxone used to block the effects of opioid overdose in emergency situations.

Higgins woke up briefly but was later declared dead at a local hospital.

The Cook County Medical Examiner's Office said Monday it must conduct more tests in Higgins' autopsy to determine the cause of death, including cardiac pathology, neuropathology, histology and toxicology testing.

Christopher Long, 36, and Henry Dean, 27, two guards who were with Higgins at the time, were arrested on unrelated gun charges, according to the Chicago Police Department. Arrest records for the men are not available and it is unclear whether they have attorneys.

Dean allegedly told police he had two guns and a high-capacity magazine on him at the time. A third gun was found in a camera case among Long's possessions, though he denied owning it, according to police.

Higgins, a Chicago native, was signed to Interscope Records and considered at the forefront of the emo rap scene. He released a collaborative album in 2018 with Future before releasing his debut record, titled "Goodbye & Good Riddance."

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The album's title began trending on Twitter shortly after TMZ first reported the news of his death. Fans and fellow artists mourned Higgins' death on social media, remarking on the tragedy of his young life cut short.

Ellie Goulding, who worked with Higgins on the song "Hate Me," wrote on Twitter that Higgins was "such a sweet soul."

"I'll always remember meeting you and your family on the video set and thinking how close you were," Goulding said. "You had so much further to go, you were just getting started. You'll be missed Juice."

Drake, who also rose to fame at a young age, posted a photo of Higgins on Instagram on Sunday.

"I would like to see all the younger talent live longer and I hate waking up hearing another story filled with blessings was cut short," Drake wrote.

Higgins once rapped about the short lives of artists in his single "Legends," in which he said he didn't want to be known as a legend because "all the legends seem to die out."

"We keep on losing our legends to the cruel cold world," the lyrics said. "What is it coming to?"

Another lyric from the song, "What's the 27 Club? We ain't making it past 21," also made the rounds on social media as fans mourned.