The note was released by the city of Chesapeake on Friday in an update on its investigation into why the suspect, identified as 31-year-old Andre Bing, began firing on workers gathered in a break room before their overnight shift late on Tuesday.

Bing, who was team leader for the shift, was armed with a handgun when he shot some but not all of the employees assembled in the break room, witnesses and police said, raising the prospect that he may have targeted individuals.

In a search of his home, investigators found ammunition and various items related to the 9mm handgun, including a receipt, according to the update from Chesapeake, a city of 251,000 people about 200 miles (320 km) south of Washington.

"The gun was legally purchased from a local store on the morning of Tuesday Nov. 22. He had no criminal history," the city said in a statement on Friday.

In his note, Bing made reference to an unspecified work failure on his part and perceived slights from co-workers, who he felt were mocking him. He said he believed his phone had been hacked and "was giving the worst feeling imaginable."

"The associates gave me evil twisted grins, mocked me and celebrated my down fall the last day," he wrote. "That's why they suffer the same fate as me."

Bing also wrote in the document titled "death note" that he planned to spare a person, whose name was redacted, because she had a special place in his heart, citing his own mother's death from cancer.

Asked to comment on Bing's note, Walmart said in a statement: "There is nothing that can justify taking innocent lives. Our focus continues to be on the families who are grieving and supporting our associates through this difficult time."

In addition to the seven dead, including Bing, two people are being treated in area hospitals. One is in critical condition and one's condition is improving, the city said.

The Chesapeake shooting came on the heels of last weekend's massacre in Colorado Springs, Colorado, where a gunman killed five at an LGBTQ nightclub.

The United States averages two mass shootings per day, when defined as an incident killing or injuring four or more people, according to GunViolenceArchive.org.

(Reporting by Nathan Layne; Editing by Paul Thomasch and Daniel Wallis)