One of them, Mamadou Sy, said in his complaint: “Directing himself towards the West Africans present, he said, ‘Wow, there are a lot of Africans, and I don’t like some of the faces I see here.’ We felt as if he was threatening us.”

Image Didier Kane Barrault, one of the complainants. Credit... Dana Romanoff for The New York Times

Most of the employees said they had been repeatedly disciplined for not meeting production requirements. Eventually, they were fired. Most of the workers had never been reprimanded before, and non-African workers were not subject to the same criticism, they said.

Mr. Sy, 61, said he was fired in September after his supervisors told him he had to greatly increase the number of boxes he was stocking. He was not physically able to do so, he said.

“I worked here for more than three years and never had any complaints about my job,” he said. “Now, we have all been getting fired. We felt it was racism.”

Ophelia Hinojosa, a former assistant night manager at the Wal-Mart in Avon, said her supervisors had pressured her to discipline the men for not working fast enough, even though she believed they performed well.

“They were trying to get most of the Africans out,” said Ms. Hinojosa, who quit in April because, she said, her job had become too stressful. “A lot of them had been there for a long time. They weren’t being treated right.”