It happened around 8:30 p.m. Saturday on the campus located in the 1200 block of North DuPont Highway.
Officials say the gunfire erupted during a school-sponsored cookout for the university's fraternities and sororities.
"Someone got trampled and I heard gunshots. It was just a horrific event," junior Davontay Phillips said.
All three people shot were taken to Kent General Hospital in Dover with injuries considered non-life-threatening.
Students were told to stay inside their dormitories and non-students were asked to leave campus.
The victims were not DSU students.
Partygoers took to social media to show the moments after the shooting.
Students, who didn't want to be identified, told Action news that numerous then fights broke out.
"It was too much commotion. I just heard gunshots and then you just see everyone running. Everyone could hear the sound pretty much and just started running from that," said one student.
Authorities have a description of the suspect but no arrests have been made.
But the violent weekend didn't end there.
A second shooting happened at a nearby apartment complex.
The complex houses mostly students who say someone fired a gun into the air. Fortunately no one was injured.
Neighbors across the street were startled.
"I just heard some shots about 1:15 in the morning. I heard some shots across the street and there was a lot of people but I never saw that many people," said James Durham.
While no suspect has been named, students say people who are not associated with the school started the trouble.
"It saddens me because I know students at Delaware State University. We do know how to conduct ourselves properly, but when you bring other people that are outside of the university, and they don't know our core values, that's when it becomes a problem," said Phillips.
It's unclear if the two incidents were related but the university's police department is handling the investigation.