Police said gunfire erupted inside the Maple Leaf Apartments in the 700 block of Burr Oak Lane around 3 p.m.
A 27-year-old man, whose identity is being withheld, was pronounced dead shortly after arriving at the hospital, University Park police said.
Two other unidentified gunshot victims in their 20s are also being treated at an area hospital. Their status is unknown at this time.
"This is unfortunate, but it is a targeted incident," Mayor Joseph E. Roudez III said. "There is no immediate threat to the residents of the complex or the general public. We extend our prayers to the victims and their families."
The investigation is ongoing.