Three Minneapolis police officers were also injured, including two of them from gunshot wounds, police Sergeant Garrett Parten said at a press conference on Wednesday evening.
All three officers are in stable condition, according to Hennepin County Medical Center.
A 911 call about shots fired at the building came in just after 4.30pm and officers entered the building three minutes later to find victims inside the high-rise, Parten said.
They heard more gunshots and followed them to a higher floor, where they found "a haze that significantly limited their visibility," he said.
"This is a tremendously tragic event and our thoughts and prayers are with the families, the loved ones of those who lost their lives, those who were injured and with the injured officers and their families," Parten said.
One of the victims was fatally shot at the scene, and one died after arriving at the hospital, he said.
Parten said it was not immediately clear how the shooter died.
Hennepin County Medical Center said it received seven patients but didn't share additional information about the conditions of those wounded.
Julius Bailey was sitting outside of his apartment building when he heard gun shots and saw a man he recognised as a resident of the building holding a pistol. Bailey said he heard a woman screaming and immediately started running away. He said he counted eight shots.
Bailey said he recognised the man holding the gun because he was someone who was known for showing off his weapon. Bailey said he has tried to avoid the man since moving into the building in June.
"I could tell he was trouble," he said.
Chris Miller, who also lives in the apartment building, said he heard a rapid succession of gunshots and quickly ran outside for safety. He said he believed he knew who carried out the shooting and that he encountered someone in the hallway with a handgun earlier this week and reported that person to management.
Video posted to social media showed police aiming rifles upward at an apartment tower near the Minneapolis Convention Center. Officials warned residents to avoid the densely populated Loring Park neighbourhood nearby.
Minnesota Governor Tim Walz said on social media that state officials were on the ground helping local law enforcement respond.
"Grateful to law enforcement actively working to ensure the safety of our neighbors in Downtown Minneapolis this afternoon," he wrote.
"Minnesota is praying for our first responders."
The FBI is responding to the shooting and "will offer any and all resources necessary to assist local authorities," director Kash Patel said on X.
The area was secured and there is no longer a threat.
15°C