TULSA, Okla.  — Less than a week after an unarmed black man was shot dead by a white police officer on a Tulsa street, prosecutors charged the officer with first-degree manslaughter, a decision that may prevent unrest in a city with a long history of tense race relations.

Tulsa officer Betty Shelby “reacted unreasonably” when she fatally shot 40-year-old Terence Crutcher on Sept. 16, prosecutors wrote in an affidavit filed with the charge on Thursday. Police also acted quickly to provide videos of the shooting to black community leaders and members of Crutcher’s family and then released them to the public.

Shelby was booked in the Tulsa County jail at 1:11 a.m. Friday and released 20 minutes later after posting $50,000 bond, according to jail records.

Crutcher died from a “penetrating gunshot wound of chest,” the Oklahoma state medical examiner’s office said Friday, classifying the death as a homicide. Spokeswoman Amy Elliott said a full autopsy report and toxicology results are not yet complete.

The swift action in Tulsa stood in contrast to Charlotte, North Carolina, where police refused under mounting pressure Thursday to publicly release video of the shooting of another black man this week and the National Guard was called in after two nights of violent protests. Demonstrations in Tulsa since Crutcher’s death have been consistently peaceful.

Tulsa Mayor Dewey Bartlett praised the police department for quickly providing evidence to District Attorney Steve Kunzweiler’s office.

“These are important steps to ensure that justice and accountability prevails,” Bartlett said in a statement. “We will continue to be transparent to ensure that justice and accountability prevails.”

Phil Turner, a Chicago-based defense attorney and former federal prosecutor, said the motivation of prosecutors in Tulsa may have been partly to allay outrage and avoid the kind of violence Charlotte has seen.

“But I don’t think the charge was only to give the crowd some blood. … No. I think (prosecutors) must have thought charges were warranted,” he said.

If convicted, Shelby faces between four years and life in prison.

Crutcher’s twin sister, Tiffany Crutcher, said her family is pleased with the charge, but she and her attorneys want to ensure a vigorous prosecution that leads to a conviction.

Attorney Damario Solomon-Simmons said: “We are happy that charges were brought, but let me clear — the family wants and deserves full justice.

“Not only for this family, not only for Terence but to be a deterrent for law officers all around this nation to know that you cannot kill unarmed citizens.”

Shelby’s attorney, Scott Wood, did not immediately respond to telephone messages seeking comment on the charges.

Dashcam and aerial footage of the shooting and its aftermath showed Crutcher walking away from Shelby with his arms in the air. The footage does not offer a clear view of when Shelby fired the single shot that killed Crutcher. Her attorney has said Crutcher was not following police commands and that Shelby opened fire when the man began to reach into his SUV window.