"In the police report you have so far, there is no description of a threat he received," Mr. Tate said. "So we have a real problem with that. But this has been a national discussion for the past two years. There is this perception that a black man is automatically feared."
The police department said in a brief statement on Monday that the investigation into the officer-involved shooting was not complete. Mr. Tate could not be reached on Monday for comment.
The shooting has revived questions about the effects of police training and race on communities, especially in the St. Louis area, where police killings of black people in recent years have had national consequences. In August 2014, a white officer from the Ferguson Police Department fatally shot Michael Brown, who was 18 and black, in a northern suburb of St. Louis.
The shooting of Mr. Brown led to protests and calls for police reform nationwide, particularly after a grand jury did not indict the officer, Darren Wilson. Two months later, protesters marched again in St. Louis over the death of another young black man, Vonderrit D. Myers Jr., 18, who was shot after what the authorities called a "physical altercation" with an off-duty St. Louis officer who was patrolling the city's Shaw neighborhood for a security firm.
In August 2015, tensions flared after the police said an officer shot an 18-year-old St. Louis man, Mansur Ball-Bey, after a foot chase by two white officers after he pointed a gun at them.
In an interview on Monday, a state senator, Jamilah Nasheed, questioned the justification given in the police statement for the black officer's shooting. Saying that an officer feared for his safety, she said, can be a blanket excuse to help absolve blame - to "get out scot-free."
"What is really disheartening, especially for the African-American community, is that we are still trying to recover from the police-involved shootings," she said. "And now to see the police officers shooting their own men in blue by way of what they call 'friendly fire'? It is telling that white men in blue suits are afraid of black men.
"The discussion is going to have to be had about sensitivity training across the board," she added. "If you are going to interact with African-Americans, the first thing that you should not be afraid of is the African-American."
The city has not had a permanent police chief since April, when D. Samuel Dotson III retired.
This year the city also got a new mayor. When Mayor Lyda Krewson took office in April, her mandate included trying to "rebuild the frayed relationships between law enforcement and our community," The St. Louis Post-Dispatch reported. On Monday, she said at a news conference broadcast on social media that public meetings and citizen advisory meetings were taking place to find a new police chief, a process that might take up to nine months.
Asked about the June 21 police shooting and Mr. Tate's remarks about blacks being treated as criminals, she said:
"My understanding of this situation - it was a very intense volatile situation, with a lot of gunfire going on. But if it was friendly fire, then certainly that was a terrible accident."