Fred Barragan, 35, was identified as the man killed during a police shooting Saturday morning at First and Soto streets.
Officers patrolling in the area heard gunshots and responded. Police said Barragan was seen running from the location.
Authorities said they tried to stop him and eventually an officer-involved shooting occurred. They said a gun was recovered at the scene.
The group of people at the plaza said they were there to ask for more accountability from police and protest fatal officer-involved shootings.
Organizer Caro Vera said the family hasn't received many details about the shooting. She said his family told her they had dropped him off at the Metro station nearby.
"He should not be dead. He should have been able to jump on that train and go wherever he needed to go," she said.
Authorities said shell casings were found in the area of the shooting and there was evidence of another shooting at First and Breed streets. But it was unclear if Barragan was involved in that incident.