An official cause of death has not been revealed.
"We are devastated at this news," Dayton coach Archie Miller said in the school's release. "Any death is a tragedy, but for someone so young, who worked so hard to have his dreams within reach, it's hard to put into words how painful this is. Our hearts and prayers go out to Steve's family. My family, our team and our staff will have to pull together, not only in support of Steve's family, but in support of each other at this terrible time."
McElvene, who set a Dayton single-season record in 2015-16 with 56 blocks, collapsed on Thursday and could not be resuscitated, according to Jamal Howell, who coached McElvene's AAU team, the Spiece Indy Heat, and grieved with family members at McElvene's home Thursday.
According to Howell, relatives said McElvene was with a neighbor when he suddenly fell to the ground. A medical professional in the area went to the home and performed CPR before paramedics arrived, but McElvene did not regain consciousness.
Howell said McElvene had expressed excitement about returning to Dayton to complete summer schoolwork and continue preparations for next season.
A 6-foot-11, 268-pound center, McElvene averaged 6.1 points, 5.6 rebounds and 1.7 blocks per game in his first season with the Flyers after redshirting the previous season. He finished with six points and six rebounds in Dayton's NCAA tournament loss to Syracuse in March.
Howell said McElvene developed late in his prep career only after recognizing his potential. Once he realized his talent, however, he made great strides on the court and drew the interest of multiple high-major programs.
Howell said he's trying to console former players and staffers who loved McElvene, many of whom texted and called Thursday afternoon as he arrived at McElvene's home.
"They wheeled him out," Howell said. "That's when I lost it, when I saw my big fella get wheeled out."