"Gunman on campus. Shelter in place immediately," the warning read.
Wilmington police said they were searching for a man on campus who robbed four people at gunpoint.
Officials told the Associated Press that authorities were using a helicopter and a K-9 unit to find the man, who was last seen armed with a small-caliber handgun headed toward campus from about a block away.
The alert was issued just before midnight EDT. In the alert, people were advised to stay away from windows and lock doors. It also advised to continue monitoring their cellphones and the website.
The alert, officials said, was issued as a "precautionary measure."
In August, another situation involving a gunman on campus raised concerns from university officials who said the school's emergency alert system failed to properly notify the campus as police searched for a man accused of a shooting in a nearby apartment complex.
The Associated Press contributed to this report.