“He kept on shooting and shooting and shooting. He shot one of my co-workers in the head and then shot one of the customers in the stomach,” Dickerson said, adding that the shooter appeared to have a military-style rifle.
“I'm a little shaky but I'm OK. I got God on my side,” Dickerson said.
The gunman, who was believed to have acted alone, was found dead of a self-inflicted gunshot wound in a parking lot outside the store, Lane said.
“We are waiting for some special equipment to search that vehicle as well as the property that is on him,” Lane said about two hours after the bloodshed, which erupted about 1:30pm (1830 GMT).
Lane said some of the surviving victims sustained “very serious” injuries. All were taken to area hospitals, he said. WREG-TV said at least five were listed in critical condition.
Thursday's violence was the latest in a string of deadly workplace mass shootings that have erupted in US cities, claiming dozens of lives and leaving many more wounded this year.
Ten people were killed in March when a gunman opened fire at a supermarket in Boulder, Colorado.
Kroger Co, a major US grocery chain, issued a statement offering “our thoughts, prayers and support to the individuals and families of the victims during this difficult time.”