Police were called to a property on Brooklyn Rd about 3.30pm on Sunday and a person was taken to hospital with moderate injuries.
Witnesses reported hearing what they believed was a gunshot before the fall, but police at the time said that information had not been confirmed.
Detective Senior Sergeant Lee Underhill had now confirmed a shotgun was fired.
"While nobody was hit, we believe the incident targeted a specific individual, who suffered moderate injuries fleeing to safety," she said.
"It is concerning that an offender has discharged a firearm in a highly populated apartment building and we are aggressively pursuing every lead in order to locate the offender."
There would be more officers in the area to reassure the community, she said.
Underhill urged anyone with information to contact police.
