A 1-year-old boy was killed after a police officer in northern Mississippi shot at a vehicle while responding to a shoplifting call at a Walmart store this week, the authorities said.

It is not clear what transpired before the shooting on Sunday in Senatobia, the county seat of Tate County, about 40 miles south of Memphis. But the Mississippi Bureau of Investigation said in a statement that officers with the Senatobia Police Department responded to a shoplifting call around 2 p.m. and encountered two people and a child “fleeing from the store into a vehicle.”

The state agency, which declined to answer questions about the shooting, said the officers had tried to stop the vehicle, “but the driver drove in the direction of the officers, almost striking one.”

An officer, whose name has not been released, then fired at the vehicle as it fled the scene, the bureau said. The vehicle eventually arrived at a hospital, where the child was pronounced dead, the authorities said. The coroner’s office in Tate County identified the boy as Kohen Wiley, but declined to specify a cause of death, citing the ongoing investigation.

Ben Crump, the high-profile civil rights lawyer, said he was representing the Wiley family. He said in a statement that the boy was with his mother and a family friend at the time of the shooting, and that the friend was critically injured.

Mr. Crump said that Kohen’s mother had not been charged with any crime and that she was “trying to communicate to officers that there was a baby in the car,” but they fired anyway.

“We intend to seek justice for baby Kohen and the life that was stolen from him,” Mr. Crump added.

The authorities have not released the names of the two adults in the vehicle.

Video obtained by a local TV news outlet appears to show a snippet of the incident. In the video, a vehicle can be seen driving away from officers chasing after it. The passenger-side door is briefly swung open for a moment. The door is then shut as the vehicle drives off. At least three law enforcement officials are visible in the footage.

In a statement the Police Department said it was committed to “full transparency.”

“As the investigation progresses and facts are verified, we will share as much information as possible,” the department said.

The shooting prompted outrage in Senatobia, a small city of about 8,000 residents. On Tuesday, dozens of people protested outside the Walmart. Videos show law enforcement officers standing in front of the store’s sliding doors and deploying a chemical irritant to disperse the crowd.

Several residents were planning to pack City Hall during a scheduled meeting on Tuesday evening and demand answers about the shooting. On Facebook, the hashtag “#JusticeForKohen” was starting to spread.

“Make no mistake, this is a very tragic situation,” Sean Tindell, commissioner of the Mississippi Department of Public Safety, which oversees the bureau of investigation, said in a news conference on Tuesday evening. He said agents were working on collecting evidence, including security footage from Walmart and officers’ body-camera videos. “I know this is a very frustrating time, but maintain patience as this process is done.”

The Mississippi Bureau of Investigation will share its findings with the state attorney general’s office.

Mr. Tindell said that the agency would release its findings, including available footage, when the investigation was complete. He did not say how long that might take.

The Tate County Sheriff’s Office said in a statement that its deputies were present during the Walmart parking lot shooting because they were dealing with an unrelated incident before their assistance was requested.

LiCole Wiley, whose husband is Kohen’s grandfather, said in a brief interview that she had not spoken with the child’s mother since the shooting, or with other relatives closer to the immediate family. She did not have more information on what led up to the shooting.

“We’re all feeling shocked,” she said. “Justice for Kohen is all I have to say.” Several other relatives did not immediately respond to requests for comment.

Walmart did not immediately respond to a request for comment.