The violence was reported about 2:30 a.m. near Cal Anderson Park, the Seattle Police Department said in a statement.
One victim, described as a 19-year-old man, was declared dead at a hospital, and the other, described only as a male, was being treated for life-threatening injuries, the department said.
"Officers attempted to locate a shooting victim but were met by a violent crowd that prevented officers safe access to the victims," Seattle police said. "Officers were later informed that the victims, both males, had been transported to Harborview Medical Center by CHOP medics."
At a noon coronavirus news conference, Gov. Jay Inslee said he wasn't aware of the details of the attack.
"One way or another we have to be able to provide protection for people all over the state of Washington, including that particular area," he said, NBC News reported.
The zone was set up as an extension of demonstrations seeking racial justice after the death of George Floyd. A police station about a half-mile from the attack is inside the area and has been abandoned.
Police on Tuesday installed concrete barriers to protect those within the zone. On June 7, a man allegedly drove into the area and opened fire on another man, injuring him. A suspect, Nikolas Fernandez, 31, was charged with felony assault.
No one has been arrested in Saturday's attack.
"Homicide detectives responded and are conducting a thorough investigation, despite the challenges presented by the circumstances," the Seattle Police Department said.