Police also say the victim "has been uncooperative" with investigators.
Ottawa police were called to the shopping centre at about 3:40 p.m. ET, where a male victim suffered a single gunshot wound to the foot.
Duty Insp. Mark Patterson said two people who were at the scene were taken into custody for an interview with the guns and gangs unit, which is searching for two more people.
Police say the victim is known to them, and they believe the shooting was a targeted attack.
After the Friday afternoon shooting, mall management closed stores around 6 p.m. "in support of and out of compassion for the employees currently working," according to police.
No vehicles were being allowed in, but parents wishing to get their children were told to use the west entrance.
A post on the mall's website says they would be open for regular business hours starting 9:30 a.m. Saturday.