It happened at the 10-story Morrison Residence Hall. Officials have ruled his death a suicide.
Allison, 21, was a junior from Cornelius who played wide receiver and was working towards a degree in management.
"Demitri was a talented young man with a bright future who was loved by his teammates. We mourn his loss deeply and we pray for his family and loved ones," said Athletics Director Dave Blank in a statement.
Our thoughts and prayers go out to Demitri Allison's family and friends and the entire Elon community. https://t.co/q3DbmXS6WU— UNC-Chapel Hill (@UNC) November 12, 2015
Elon was planning a gathering at 4:30 p.m. Thursday in Rhodes Stadium for students, faculty, staff, and community members.
The school is also providing counseling for students who need it.
In an email to students, school officials said Allison had left Elon Tuesday and "and his teammates, friends and family asked police to look for him because they were concerned for his well-being and emotional state."
"The death of any student is devastating to our community, especially in situations like this, and we want to reach out to friends and acquaintances who knew Demitri. The loss of a classmate, friend and student reminds us that the life of each person in our community is precious," said Smith Jackson, Vice President for Student Life.
Demitri was a Phoenix football player. His coaches, teammates and our entire community mourn his loss.— Elon University (@elonuniversity) November 12, 2015