JEFFERSONTOWN, Ky. -- A federal prosecutor says the shooting at a Kentucky grocery store that left two people dead is being investigated as a possible hate crime. Fifty-one-year-old Gregory Bush has been charged with murder and other crimes in the fatal shooting of two shoppers at a Kroger store on Wednesday afternoon.

Both victims were black. Bush is white.

U.S. Attorney Russell Coleman in Louisville said Friday that federal investigators are examining if there were any violations of federal law, "which includes potential civil rights violations such as hate crimes." The FBI is investigating alongside local police.

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Coleman said in a prepared statement that the shootings "are not being taken lightly by the United States government."

Gregory Bush WLKY-TV

Bush was recorded on surveillance video apparently trying to get inside a predominantly black church before the fatal grocery store rampage, police said.

An arrest report says Bush walked into the Kroger, pulled a gun from his waist and shot a man in the back of the head, then kept shooting him multiple times "as he was down on the floor." The report says Bush then reholstered his gun, walked outside and killed a woman in the parking lot. Each victim died of multiple gunshot wounds, Rogers said. Rogers said Bush was standing at arm's length when he shot the woman in the back of the head.

A man carrying a concealed weapon who happened to be in the parking lot challenged Bush, and police say the suspect then "began firing wildly" at him, putting other shoppers in the parking lot in danger. Neither man was hurt in that confrontation, Rogers said.

Bystander video shows a white man in a distinctive neon-yellow shirt trying to drive away while an officer chases after him on foot. Many more officers converged on the scene and made the arrest just a few hundred yards from the store.

Bush was jailed on $5 million bond Thursday on two counts of murder and 10 counts of felony wanton endangerment.

After releasing a photo of the suspect, authorities received a tip from an employee of the city of Jeffersontown who said he thought he saw Gregory Bush outside the First Baptist church prior to Wednesday's shooting, city police chief Sam Rogers said. The video confirmed Bush's presence, Rogers said. The church is headed by a black pastor and has a large African-American membership.

Bush "appeared to try to gain access to the church," Rogers said.

The information came as news media outlets reported that Bush made a racial comment after the deadly shooting. Rogers said Thursday it was too soon, however, to say whether the shooting was racially motivated.

Ed Harrell was quoted by the Courier Journal of Louisville as saying he was waiting for his wife in the parking lot when he heard gunshots and grabbed his revolver. As he crouched down, he said he saw the gunman walk "nonchalantly" by with a gun by his side. Harrell said he called out to ask what was going on, and the gunman replied: "Don't shoot me. I won't shoot you. Whites don't shoot whites."

Rogers said police "are aware of that statement and are evaluating any factors that may come into play with" it.

"I can't speculate on motive at this time," the chief said at a news conference Thursday. "We are pursuing all avenues of the investigation no matter where that takes us or what it involves."

Bush's ex-wife is African-American, and she has received protection orders against him after violent outbursts, including an incident in 2009 when she told police he called her racial epithets during a custody exchange of their son. They divorced in 2000.

Maurice Stallard, left, and Vickie Jones, right, were killed in a shooting rampage at a Jeffersontown, Ky. Kroger store Oct. 24, 2018 WLKY

Chief Rogers said Bush apparently does have a history of mental illness, as news outlets have reported.

The local coroner's office identified the victims as Maurice Stallard, 69, and Vicki Lee Jones, 67.

Police said there didn't appear to be any connection between Bush and the victims, or any link between Bush and the Kroger store.

Stallard's 12-year-old grandson was shopping with him in the store when he was gunned down, Jeffersontown Mayor Bill Dieruf said Thursday. The boy was physically unharmed, but most certainly traumatized, the mayor said, adding, "He was there and cannot unsee what he has seen."

Stallard was the father of Kellie Watson, the chief racial equity officer for Louisville Mayor Greg Fischer. The mayor shared his outrage Thursday over what he called an "epidemic of gun violence" that "hit close to home."