According to Eurohoops sources, Ojo was having an individual practice with Partizan and the collapse happened while he was running. There have been no signs of Ojo having any health issues throughout his tenure in Serbia including any heart conditions.
Multiple reports from Serbia state that the big man was brought to the hospital from Partizan's stadium but he was showing no signs of life and the doctors weren't able to reanimate him.
After five years at Florida State, Ojo started off his professional career in Belgrade, Serbia with FMP for a year after which he played a season for Crvena Zvezda. He won the 2018 ABA SuperCup as well as the ABA League and the Serbian League in 2019. Ojo was a free agent this summer.
Hate to hear that happening to anyone so young, hated watching us go up against him, but he sounded like a really great dude.