Story highlights Spokeswoman: Staff, volunteers got calls warning of "potential civil unrest"

Agency: Charles Smith, in handcuffs, was killed after an officer saw he "had a firearm"

People gather near shooting scene afterward, holding up signs and holding hands

Police chief tells locals not to do anything "that will cause you problems"

Police say a Savannah, Georgia, police officer killed a handcuffed, armed man Thursday as the man tried to break out of a patrol car, a shooting that stirred up citizens and prompted the mayor to acknowledge that the community has "many questions."

The incident occurred shortly after 11 a.m. in the historic coastal city, Savannah-Chatham Metropolitan Police Chief Julie Tolbert said. Tolbert has asked that the Georgia Bureau of Investigation look into the shooting.

The GBI, based on its preliminary investigation, says officers arrested 29-year-old Charles Smith on outstanding warrants and handcuffed him behind his back.

Smith was put into a police car, where he managed to move his hands to the front of his body, and he kicked out one of the vehicle's windows, authorities said.

"The officers said, as Smith attempted to exit the patrol car, they saw that he had a firearm," the GBI said in its statement. "This encounter resulted in Smith being shot and killed at the scene."

A firearm was later found under Smith's body, the GBI reported.

Dozens of people gathered in a Savannah neighborhood at the shooting scene, which was cordoned off by police tape.

Some of them cried and hugged, a few appeared outwardly angry, and a handful carried signs to voice their views, video from CNN affiliate WTOC shows. At one point, many of them -- including some children -- joined hands in a circle.

"The amount of people in the street" spurred the Chatham Emergency Management Agency to send out automatic calls to warn staff and volunteers about a "potential civil unrest situation," agency spokeswoman Meredith Ley told CNN. She added that such notifications are standard for times like a parade or a marathon when there's a situation with "a large amount of people that could escalate quickly."

Savannah Mayor Edna Branch Jackson said that after talking to "the victim's family" and West Savannah residents, she shares "many of (their) questions" about the incident, concerns she has relayed to police officials.

"When the answers come, we will be open, transparent and forthcoming," vowed Jackson, who said in a statement that she is "distressed" about the shooting. "We will remain in continuous communication with the family. For now, I hope the citizens of Savannah will join me in remaining calm and patient as authorities gather the facts."

Speaking to people congregating in West Savannah, the mayor said: "This will be cleared up. This will be cleared up. We don't need anything to happen. And we are going, we are going to keep the family and the community informed of everything that is going on. Now, does that sound fair?"

Tolbert told those gathered that the investigation is "going to take time." In the meantime, "What we are asking you to do is not jump to conclusions, not make rash decisions, not ... do something that will cause you problems."

The GBI pledged it will "thoroughly investigate this incident to determine exactly what occurred." That includes an autopsy on Smith to be conducted Friday in Savannah.

"When the investigation is completed, the findings will be turned over to the Eastern Judicial District Attorney's Office," the GBI said.

David Jannot, a 10-year veteran of the Savannah-Chatham Metropolitan Police Department, has been placed on paid administrative leave pending the outcome of the investigation, police said in a statement. The police chief, Tolbert, told reporters that such leave is in line with "proper protocol."

As to Smith, the man Jannot killed, a friend described him as "cool people."

"He was willing to help out," Joe Strobert told WTOC. "He was willing. If you ... needed help, he got you."